AITAH for cutting off the relationship with my dead ex fiances family

My dead ex fiances family wants me to forgive and forget that their daughter (my exs sister) is to blame for his death.

For context, I had become pregnant with 3 kids total during our entire relationship, at about 8 months into my last pregnancy with our twins he overdosed, paramedics came and he was revived. when questioned by police I told them that his sister was the one who gave him the pills which were thought to be oxy, later confirmed in hospital that they were pure fentanyl, she admitted to giving them to him and knowingly gave him fentanyl instead of oxys. she was never charged but the family got mad at me and hated me for ever telling the police that she was who he got the pills from. Now let me say I never wanted him to take them, I just knew he was having pain in his ankle and that he had gotten some pain pills to help with the pain from his sister, which initially I was against him taking but he expressed how much pain he was having (he was born with an ankle deformity) that caused him trouble over time. Forward to a year later, he had gone out to do his morning job and decided to take more of the pills his sister gave him again, clearly not learning from the first OD. He took them and OD the second time, but no one was around to help him and he ended up dying from it. His sister was never charged or anything, she even went to his funeral and had the audacity to say at the funeral in front of everyone that just a day prior to his death he has showed up to her place, saying that he's been stressed with the work, the birth of his babies and putting a roof over our heads. she was basically insinuating that I was to blame for all his stress and the reason he was looking for something to take the edge off. Now fast forward again, its been 5 years since he has passed and his family is mad at me for not forgiving her and forgetting it. I recently cut off the entire family at this point because they're all either drug addicts or the enablers, his parents claim to be christians but still allow excuses for all the drug use in the family, because their kids can essentially do no wrong, and if they do its not their fault. I have been made out to be the enemy in the entire family because I can't forgive and forget all their wrong doings during the time of my ex fiances death. They all showed up at my house after the funeral drunk and laughing while I was grieving with 3 babies on me. I kicked them out of my house, and his niece made it about her and just talked about how she was going to "honor him at her wedding", mind you this was just hours after the funeral, within a 3 day span his family managed to make everything about them, not him. theres a lot more but I won't go into it much more, just know that I spent years thinking this all over to know if I was just being dramatic or not. But I need to know if im the wrong one for cutting them all off from me and the kids. I'll answer questions if anyone has any for me, but I honestly just need a different point of view from someone out of the picture to give me their own opinions.