aita for asking my dad to not be inappropriate with his girlfriend in our company?

My dad cheated and left my family home three years ago, after a year of living in the house as a separated couple- which was intense.

He was horrible during the separation, and I have since had to help support my mum who he blamed the divorce on (said “I forgive you for making me love another person”, and he used her depression and consequent lack of attention to get an upper hand in the divorce).

I’ve tried to get on board and support his relationship and build a relationship with his girlfriend, whom he cheated with, after feeling like if I didn’t, that I’d lose out on his new family dynamic; as she has children.

My main issue is that I’ve asked him to not conduct intense PDA while we’re near him, it’s gross and makes me and my younger brother feel uncomfortable. My younger brother is in his teens and heard him having sex the other night, when I approached my dad about the issues we have with his behaviour and I mentioned this he said ‘that’s life’.

I’ve had a couple of conversations like this, on the same topic, and walk away feeling like I’m in the wrong and am just trying to split them up, as he says. He said that ‘we don’t do it for your benefit’ and has made it pretty clear that he dosent care that his PDA makes his children feel uncomfortable, and that he will continue.

I was shocked the first time I brought it up, he was very hostile towards me and flipped it on me, I feel guilty for bringing it up and that I should be happy for him. I tried to approach him again after some inappropriate behaviour recently and the same thing happened again.

I’m seriously questioning if asking my father to respect that his children do not want to see him grope his girlfriend is a unrealistic request?

My friends and boyfriend say not but I don’t know if they’re trying to protect my feelings and make me feel like I’ve not risked our relationship for no reason. He diminishes my issue, makes me feel stupid, but it’s uncomfortable and they’re both aware that it’s weird to us - but make no conscious effort to respect our emotions.

It’s not even like I see them often together, I’ve tried to set boundaries because it took me so long to forgive my dad; and because of this I’ve only just started seeing them on a semi-regular basis. Yet when they are with us, they can’t seem to keep it to themselves. AITA ??

UPDATE: He’s asked me to go to counselling with him because he thinks I have a ‘deeper issue’ than the PDA. I think that this is just a way for him to deflect responsibility and it’s not up to me to save our relationship. WIBTA if I said no, or do you think it would be good for someone to counsel us and maybe show him his narcissism in a different perspective?