[Solved] Help with blended family please!

Hi there, this is my first time posting and am here because I am at my wits end. I apologise now if this is a long post......
I was maried twice, no kids, never wanted any, and then met a beautiful women at work, she to was divorced and had 2 kids girl 10 and boy 5. We fell in love and took things really easy, I met the kids and over time I started to stay over weekends. We all got on fine, both kids had issues the girl major major tantrums since she was a baby and the boy, his mum believes (as do I) has some form of mild ADHD. The kids constantly fought, not physical (although on occassions it has been). The bio was on the scene and had them every other weekend and was paying maintenance.

This was all new to me as not really been around kids much and I was 38 years old. Anyway after 18 months I moved in with them and whilst I had to make major changes to my lifestyle I still had freedom to go to gym 3 times a week after work and have my own space. Also we had every other weekend to spend just the 2 of us which I so looked forward to. After time the bio father was erratic in him having the children, maintenance stopped and he moved someone in who had 2 kids and they took over his kids rooms. I started to be very resentful as I work hard and was supporting his children and he couldn't be bothered with them. This will have messed them up and continues to do so.

During this time I wouldn't say I had a close relationship with either kid, which I was fine with, we would do things as a family at weekends but I didn't really do any one on one time with either - this was completely fine with all of us I took on a step parent role but tried to leave discipline to the mum. The kids continued to have issues and fight, the eldest is very intelligent girl but her relationship with her mum isn't great, they often fight and shout. The boy is frustrating, not listening, have to ask him several times to do something and end up shouting at him. Their mum is quite good with discipline and will ground them, remove priveleges etc. They can both have sudden mood changes and temper tantrums.

Anyway after a year of living together, despite both of us not wanting children together before, we decided to try - up to this point in my life I had always said that I did not want children but my view changed after I met this beatiful women. We fell pregnant really quickly and had many discussions about how we must try not to let the fact that I am having my own baby mess my relationship up with the 2 kids. The bio father continued to be very erratic, many times we wouldn't even know if he was going to turn up to pick the kids up, his relationship with his ex (their mum) deteriorated from amicable for the kids sake to [censored] because of how he had changed and ceased supporting. If I had not been on the scene I dred to think where they would have ended up as whilst she works part time, she would not have been able to continue with her mortgage etc. I started to really hate my stepson at this point, he irritates me, everything he does from finding poo and [censored] very hilarious to making up stupid songs, falling over on purpose for attention etc. I started to resent my time at home and would look for excuses not to be there so I did not have to spend time with him. I find myself leaving a room if he comes in. I was starting to lose patience with him very quickly and after asking things twice I would end up telling him off or shouting. I suppose I went through periods of wondering if I should stay or leave as I hated the situation so much but I love my wife so much and my stepdaghter I am fine with.

We married and our baby son was born, and that is where everything started to go really wrong. My son is my life and I want to do everything I can for him and spend what little time I get after work with him and weekends. The boy is now 9 and he continues to be a pain. I am not interested in him in the slightest and have tried to disengage. I try to be polite and sociable, but this is so hard, he has no qualities which I admire. He is a mummy's boy, has few friends, doesn't stick at anything, loses his rag if something doesn't go right first time, doesn't enjoy sports. All he talks about is his [censored] xbox! I struggle with my role, I try to keep out of arguments, discipline but when I hear the way they talk to their mother then it's like a red rag to a bull. Where my wife used to find my stepping in very supportive she now sees it as an intrusion and that I am picking on her kids. One episode which really sticks in my mind was my sons first birthday, whilst my son didn't understand what was going on the boy had to take over and unwrap the presents and start to play with the toys. I was not impressed with this and asked him to step back and leave my son to open and play with his toys first. My wife did not like this and said he is just a boy and was playing. What is wrong wanting my son to open and play with his toys on his birthday?

As I said, we were never close and didn't do things one on one but my relationship with my wife has deteriorated as a result. She says I have changed since my son was born, I don't do anything with her son and am always on at him. I admit I watch him constantly when he is around my son as I am waiting for him to do something wrong and I then end up telling him off. He has bad habits which I do not want my son to pick up. He also has to take over everything. If I am playing with my son he has to be there involved, I don't want him to be, it's my precious time with my son! My wife now watches me like a hawk and is over protective of her eldest son and it seems like I am on a downward spiral, I still can not tolerate her son, I try to bite my tongue but can't always, my wife then blames me for being horrible to her son. It's got to the stage where she has said that if she knew this is how things would turn out she would not have got together with me let alone have children. (we have since had another son so that's now 4 children in total) and if I make her choose then she will choose her son.

Whilst I recognise my actions play a large part in this, I am made to feel everything is down to how i treat her son. If he is in a bad mood or getting into trouble at school then it's because how I treat him. Whilst I do not want a close relationship with him I do want to have a relationship which keeps my wife happy - that's all, if she is happy then I am happy! I have been for counselling on my own and whilst this helped me, it hasn't improved home life. I have read books and try to incorporate the good advice but it is so hard when you see no reward. I would rather channel all my love and time to my sons, not the stepkids. My wife will always say " he is just a 9 year old boy and you are the adult".

I feel so alone and see my marriage and the love of my wife to me slowly slipping away because of him. We do not argue about anything other than him and I don't know what to do. I can see as my sons grow up I will be tougher on them than I am/can be with her 2 other kids becasue I do not want them turning out like them and being disrespectful to anyone. I feel so helpless and alone...