Am I overreacting?

Okay, this is going to be a long one so stick with me. My SO’s mother is a wonderfully sweet woman. She has never been anything but kind to me, but she has no idea how to be a responsible parent. Now before everyone jumps down my throat, hear me out. I understand that a parent is not responsible for the choices of their children, but all three of her children are recovering drug addicts, my SO included.

Her daughter had a baby at 13 and she allowed her to move out of town with the 18 year old father and his family. The daughter now has five kids, a marriage that requires a visit from the police at least once a month for domestic violence issues (from both sides) and a meth problem that has caused psychological issues with each of her children. We live in a town of 2,000 so it’s not like this sort of thing happens every day.

Next, my SO’s brother has been in and out of prisons/juvenile detention centers/rehabs since he was 14. He’s lost custody of his daughter, who was born an addict baby. His current wife (second, both meth users) is serving a year long sentence in prison as they were found squatting in an abandoned house, naked and with loaded needles.

Last but not least, my SO. He developed a severe opiate pill addiction at 14 after his older brother was allowed to move back into the family home in the middle of full blown active addiction. My SO’s was conceived in Florida (we’re in the midwest), but his mother consequently moved here while pregnant after finding out my SO’s bio father was actually only 17. My SO’s bio dad is also a drug addict with severe mental issues and eight other kids, that we know of.

While pregnant with my SO, his mother met a married truck driver (how she ended up in our small town), and hooked up with him. They later married after he left his wife and son, and he adopted my SO. He’s no winner either tho, as he did meth with my SO when my SO was 16 and has lost idk how many jobs due to failing drug tests. They are now divorced and all he does is drink and annoy his neighbors by blaring his depressing ass rock music till five in the morning while living near many young families.

Last but not least, my SO has a 13 year old nephew (from his sister) and my SO’s mom has a boyfriend with a 13 year old daughter. My SO’s mother’s boyfriend shares custody with ex wife so she stays with them every week for half of the week. My SO’s mother allows her grandkids to come over whenever as she knows her daughter and son-in-law are a mess. Somehow, my SO’s nephew and the boyfriend’s daughter stared dating months ago.

Fast forward to New Years eve, my SO’s mother is drunkly complaining to me (normal) about how she thinks her grandson and the boyfriend’s daughter are having sex because they are left alone a lot. Unfortunately, the grandson had came to my SO a few days prior and asked him to buy condoms for him and admitted to my SO that he and his girlfriend had been sexually active for months.

My SO had been trying to figure out how to bring this up to his mom and found that to be a good opportunity. He confirmed what she thought. Of course she had her boyfriend ask his daughter and she denied it, but the grandson broke down and admitted to it all. Even after having him admit it to them, SHE STILL DIDN’T TELL HIS PARENTS.

My SO and I are currently expecting our first child in June. We had dinner at his mother and boyfriend’s house last week and the grandson and boyfriend’s daughter came up. Her exact words were “I’m going to be so mad if she gets pregnant, but we’re just going to stay out of it and let it be.” Excuse me? 😅

After coming home from the dinner, I very kindly told my SO that I don’t think I feel comfortable leaving our child alone with his mother because her judgment seems to be very skewed as to what it means to be a responsible parent. When he asked what I meant, I brought up the fact that she’s basically decided her 13 year old grandson can have sex whenever and with whoever he wants and hasn’t bothered to try and dissuade him OR notify his parents. He agreed that was ridiculous but said that we wouldn’t have to worry about that for another 14 years. But to me, that really doesn’t matter. With all the other things I know, I feel like it just solidifies that her judgment is horrid when it comes to doing the right thing and being a responsible adult. I don’t feel like she is fully capable to take care of my child to the standard that she should and I don’t know how to politely say that to my SO, or if I’m just being an over protective mama. My SO will back me as he accepts logic, but short of saying “your mom has no idea how to be an actual parent and not just a friend”, I don’t know what to say. So any sort of advice would be greatly appreciated. Very very veryyyy sorry for the novel, just had to get that out.