I just see this as abusive to my mother in law. She can't see it. I have showed her the symptoms for borderlines and she doesn't seem to agree with me. I want him to get help, because he only seems to be getting worse. She is literally the kindest, most long suffering person and she still protects and defends him. She is completely committed.
You are very caring to consider helping your in laws. I have highlighted the reasons why this is not something you are able to do, unfortunately.
There are complicated dynamics between an abusive person and their co-dependent partner. While it appears your MIL is the victim, she also plays a part in the dynamics, possibly not consciously but as a co-dependent enabler.
Your FIL's behavior is the more obvious. Co-dependent behavior is seen as being kind and caring, and so it isn't perceived as being part of the issues. It's a good thing to be kind and caring, but enabling is different.
If there was any hope of change, it would likely be through your MIL deciding she wants it. We can't change another person's feelings or decisions. I understand it's hard to observe this from the outside. My parents were in a similar situation.
I want to call your attention to the Karpman triangle dynamics. My naive impulse was to step in to try to "rescue" my enabling father from the behaviors of my BPD mother, and we did this several times in different situations. The victim-rescuer(enabling) bond between your in laws is very strong. They will likely align together against you.
It's actually a good thing that your FIL isn't interested in the grandchildren. They need to be protected from abusive people. Unfortunately this may also mean protecting your children from both of them at times, due to the interactions between them. It's a tough balance- you want to show respect for grandparents while also not exposing them to these dynamics. This may mean spending less time around them, or limiting contact to public spaces where others are around as often pwBPD are more likely to behave better when others are around.
This is a tough situation because I wanted to have a relationship with my father and also for my kids to have one with him- and they did. But this had to involve some boundaries with BPD mother which she didn't like. Although I perceived them as separate people, they were actually enmeshed and functioned as if they were one person. This is important to recognize. Your in laws function as one person with your FIL's feelings taking precedence.
Do the best you can, and be kind to your MIL but your task is to keep your family intact and safe from any abuse and to protect your children.
