Boyfriends son called me mama

I've been with my boyfriend 2 years. When we started dating his son was 3 years old. There's a lot with his baby mama but since their son was a year old the judge told her she's only allowed 3 days a month with their kid. She's done a lot. My boyfriend 21. His baby mama is 27. Their son is 5 so you can do that math. That wasn't even why custody is the way it is. She would go live and post photos with illegal guns and her boyfriend and her with guns. She was posting Instagram stories blowing weed in their babies face. There's a lot of reasons that she only get their son 3 days a month and she continues to live her life and do stupid things. So I've been in his life since he was a toddler. We know we do want to get married and just got a place together last month. But I want to know if I should be correcting him or not. On one hand he has a mom. On the other hand she's not around 90% of the time.