@chatterbug22 don’t feel bad about only seeing this abusive family situation recently. Toxic families are REALLY good at making it seem normal & negating your feelings that it is wrong. It IS wrong.
your mum is part of the problem by turning a blind eye to what’s going on and actually facilitating it. Your dad isn’t going to get involved because he’s frightened of rocking the boat. It’s great that he likes your partner, but that’s enough. Sadly, you need to accept that the three of them are the problem.
Frankly, fuck what your sister thinks about you ruining 2022. She’s always going to find a problem with everything you do. And your mum is going to listen to the nonsense or be part of the problem.
with regard to the wedding, you CAN back out. This will unleash a shower of shit, but it is an option for you. It might mean she never speaks to you again, but that might be a very good thing.
You CANNOT reason with these people. Self-preservation means backing away, and not feeling bad about it. It is YOUR family, not YOU doing this shit. I’ve found NC really helpful with The Hag - easier because she’s not my mum.
What does your partner think? Does he want to go? Yes, he will probably want to do the ‘decent’ thing and support you, but he might have his own views of not wanting to go. And that’s OK. If you’re having counsellor together, I’d suggest that you talk about it in that safe space and back each other up. IF he chooses not to go, that’s not a rejection of you. But if he does go and isn’t included, he might not actually give a shit and is there as support.
you are able to do the wedding in your way. You don’t have to explain or justify what you’re doing. Your sister is certainly not articulating what her game is, she won’t, but you know what it is now which is a more powerful place to do.
Your sister, frankly, is trying to break you up. Pribably because she sees you have a good relationship and there’s support for you there. Your relationship and your happiness is the priority.
You will be in the dog house whatever you do - go with your partner or not with your partner. It’s really up to him (and uou!) what you do, not her. You are not “backing down” by prioritising his/your happiness. It’s a hard thing to negotiate. When is the wedding? Drop the meet ups and contact as much as you can.
Your sister will hopefully look back on her wedding and regret her behaviour, but she won’t. She feels no guilt or responsibility. I wonder about the long term happiness in her marriage. You can look forward to long-term drama there, and another reason to go low contact.
the priority is you, your daughter and your relationship. Never lose sight of that.