Toxic mom

Hey ladies, so I've post a couple times before about my fiances mother and how my fiance and her had a pretty big falling out.

Just for a quick recap, I have a baby shower this weekend and I had invited my fiances sister, shes my boss at work so the invitation was extended to everyone I work with and it's not like I have problems with her. However, my fiances mom and step dad have a problem with her, just typical family drama and they're on pretty poor terms. When my fiances mom found out that I had invited her she flipped out and said she was going to start a fight at my baby shower if she shows up and just being dramatic and petty. So I told my fiance that if his mom cant put her differences aside for a couple hours for her grandchild then shes not welcomed there. This turned into a huge fiasco and she said we always invite people to events that she doesnt like or get along with so she can't come and said we always keep our son away from her, she blames mostly me for whatever reason. (The last time she saw him was because I told my fiance we should bring him to the house so his family could see him because it had been a while.) So my fiance finally told her enough is enough. She never asks about our toddler, never sees him, calls, texts, answers phone calls or returns messages. So she got very defensive, cause I mean, the truth hurts and she called him a cock sucker and said he was dead to her and that was that. They hadn't spoken in two months.

So yesterday my fiance called his step dad because he had borrowed some money from him because his work had cut back drastically in hours and he fell behind a little bit so he was calling him back to let him know he was going to pay him back next week. While in the midst of talking to his stepdad his mother gets on the phone and starts asking him about our son and asked if he was planning on stopping by with him for Thanksgiving so she can see him. (Literally the first time in 2 years she has ever asked to see our son without us asking her if she wanted to come over or get together, so kind of a big deal.)

So my fiance said he doesnt know if she forgot what she had said to him or if shes just trying to ignore the situation and move forward. I don't think he cares either way because I know he missed his mom because regardless I mean, that's his mom and I wouldn't want to get in between the relationship between them. However, I feel like I'm just kind of over the situation and feel like she should apologize for talking to her son that way and then blaming us for our son not knowing who she is because it's not our fault. The phone goes both ways and I'm not going to chase or beg someone to be apart of my childs life. Anyway, I want him to do whatever he wants to do when it comes to having a relationship with his mom but I'm just not interested anymore. I just feel like shes toxic and blames everyone else but herself for her problems and issues and I dont care to have that around me or my kids. Am I wrong for feeling this way? Is this something I should just ignore and put a happy face on for the sake of my fiance?