r/AITAH for wanting to cut contact with my dad

This is my first time on reddit and I could really use advice, I (15non-binary) have been wanting to stop all contact with my dad. And it's not a teenager rebellion thing, my relationship with him has just been at its worst point. For context I live with my mom,her and my dad have not been together for a long time and I'm alright with that, I have been for awhile as I saw my dad regularly but as of last year I've been wanting to visit less and less. Last year my dad married his gf I'm going to call T, and I kinda forced myself to get along with her out of fear that I wouldn't see my dad if she didn't like me because he moved in with her and her 2 daughters. I met the 3 of them a few months before the wedding and in all honesty I love my younger step sisters to pieces but I can never bring myself to refer to T as my step-mom and my dad is a bit weird about it, he says that he doesn't expect me to call T mom but he's really pushy about me doing things like hug her and have one on one time with her. I never really liked T as she yells alot,often makes fun of my dad and as my dad says his day's of work are her days of as he looks after my step sisters and she does little to nothing(she is unemployed).I personally think that there relationship is kinda toxic and I don't agree with alot of there parenting approaches. My dad has never been the best dad and that still hasn't changed,I told him about all the ways I'm feeling and he seemed to understand at first. He let me start visiting for just a day and not going to his house because I don't feel safe there,I thought things would be fine and even started speaking my mind more and opening up around him but on the FIRST visit he started talking about how he didn't understand why I said that I don't like T because I've had good bonding moments with her, and I explained to him that I was just pretending to like her to make him happy but it seemed to go in one ear and out the other as he seems to think that just having a few good memories means that the bad ones like when she yelled at me a few times didn't happen. I visited him about 2 more times and he kept talking about how my step sisters miss me alot and how he wants me to meet T again and try to get along with her for real and I just feel like I'm being guilt triped and I feel pressured to fix things as soon as possible even if I'm not ready. When I talked about all the problems I had with T it was at my nanny's(his mom) house. my mom,my grandad, my uncle,my nanny and my dad and me obviously were there. While we were there my dad seemed to understand why I was upset completely and my nanny was in my corner backing me up completely in everything despite her and T being really close, but after that whenever it was just me and my dad he seemed like he thought that everything I said at my nanny's was a lie and he's always had a bad habit of thinking he's always in the right when it comes to things I say even if I'm in the right and he always acts like he knows me better THAN I DO! It's always annoyed me and I've told him about how much it upsets me but he won't stop. My mom says that I should do what I think is best for me because now whenever I think about my dad,my step sisters and T even if I'm thinking of a happy memory I just feel sad and if I view my dad as a person separate from my dad I don't like him almost at all and I feel like a terrible person for it but when I'm not thinking about them and what's happening I feel completely fine and I'm the happiest I've ever been in my life(not an exaggeration)even when I think about my step sisters I just feel sad because I can't see them without seeing T as she has attachment issues with them and refuses to be away from them for "to long". In summary I'm in between a rock and a really hard place with no clue what to do and I feel like if I want everyone to be happy again I should just pretend to be fine and act like there were no problems at all but in all honesty that's a bad habit I have and have had my hole life,my mom says I should stop invalidating my problems for the sake of others but it's basically all I've ever known. I'm not comfortable talking to my dad about it as I've not told him about it and I haven't replied to his messages for about a month and keep making excuses to not see him. I've been leaning towards not having contact with him at all but I have no idea how to tell him and I don't want to hurt his feelings, he's a bad dad but he's still my dad and I love him to much to hurt him but it's hurting me to keep contact with him and pretend everything is OK. My mom dislikes my dad so I feel like a bit of her opinion is biased and other than her I have no one to ask for help from, it's why I've come here. So AITAH for wanting to cut contact with my dad?