I'm sorry but I'm feeling a bit outraged on your behalf that your partner is behaving in this manner while you are pregnant. It just friggin astounds me how some people can completely ignore how emotional/vulnerable one can feel while pregnant and so close to term.
Ok, moving right along here.
Your partner's mother is obviously living in her own little Codie/Enabler world, so you can probably just ignore her. What she said was totally hurtful and misguided but oh well, you can't change her.
I see your process mentally, and I applaud you for coming here to work it out for yourself. I wish you a restful week and hope that you are able to stick to you guns no matter what your partner does or doesn't do.
I too struggle with wanting to get stuff of my chest, from years of anger and resentment I feel towards my XAH, but I'm slowly learning that I may never have a voice where he is concerned. He will never hear me or validate me so I might as well stop trying and trust in what I know in my heart.