Backstory: my partner (M32) and I (F33) have been together for two years.

This week we are visiting another state (the state where he grew up) where his family lives because one of his immediate family members is very ill. He has a cousin who he calls his twin because they were born four days apart and were raised together. This cousin has three children, including a new born, and has always struggled with drug abuse; i have also had issues with this, but through lots of tough lessons - my family cutting me off until I got it together - I have thankfully found peace, and I work HARD to maintain that peace.

This cousin already doesn't like me: she is the type of person who's very possessive of my partner, especially given that he's the only male child in their entire family for generations, and when she was going through a rough patch with her husband, my partner told her really bad things about me (at the time we were also going though a rough patch). But I know how important she is to him, so I did everything I could to quell my anxiety and go into meeting her during this trip with a "beginner's mindset". I was actually looking forward to it. Her and her husband and their three children (all under the age of four, with one being a two month old premature baby) picked us up so we could have a day at the beach together. That was the plan. I'm in a place I have never been before, and we don't have a car here, so my partner and I were pretty dependent on them for this outting.

Suddenly we are not going towards the beach. We cut through some alleyways, end up at a park. And the next thing I knew the cousin is walking off to the bathroom while her husband does a drug deal. With three toddlers in the car, and my partner and i stuck in the back seat. She (the cousin) was fully aware this was what was happening and did absolutely nothing to stop it (in fact, she blatantly lied about it and claimed her husband was "super clean and doing well").

I felt incredibly unsafe, and managed to hold it together til we finally got to the beach. At the beach I immediately left the group and my partner was actually supportive of that and we got back to the house we are staying at without them. He told them why we were leaving and she blamed it all on her husband, claiming he's a narcissist who forces her to do these things... except she's been using since before she met him. And my partner has always excused it by saying "she's had a hard life" (and he feels guilty for moving away).

But this was next level. Involving us in a drug deal with children in the car is NOT safe. It shows me that she has no respect her cousin (my partner), her children, or herself. And I think my partner continuing to emotionally support her and excuse her behavior is enabling her. He admitted she could turn to her grandma for help to get out of this situation with her husband, but she wont because shes embarrassed (something i also understand, because ive gone through that too). Now it is clear that no matter how unsafe she makes life for herself and her family, my partner will tell her it not her fault, she's trying, she's a good person (and this has been going on for well over ten years).

I have to protect the peace that I have worked so hard for, and i told him this. I told him he is enabling her, and i told him that I will not be involved in anything to do with her because I have to protect BOTH of us and clearly she does not respect him (so yes, this means if she ever visits us, she can not come to our house, and I will not be around her unless she is truly clean and sober).

So TLDR; AITAH for not being able to be a part of his cousin's life, after she forced us into an unsafe, illegal situation.