MIL issues.. HELP

So.. my MIL can be a little crazy, but I do love her. About a month ago, she called me and was talking about her plans to take off and stay when the baby was born for about 10 days- loved the idea. Then she ask how my husband (her son) would feel about his stepdad coming. His stepdad has been married to his.mom for most of his life but they basically have a non existent relationship- he was a shitty dad. To top it off, my MIL actually divorced him due to many years of affairs but has now remarried him. She wants my husband to" accept" him. While we have accepted the fact that they are remarried and live 9 hours away... we really don't give a flying fig for his stepdad. He ignored our whole family including our 4 yr old little boy during our last visit. So... when MIL asks if my husband would care if he comes too... I say" well I'll talk to him about it." I talked to my husband about it and we mutually decided that it would be awkward for both of us to have him at the hospital and then at our home while I'm trying to recover from a csection. I called my MIL back and me and husband both respectfully told her Our wishes. I thought she accepted it, now fast forward to a week later, we get a crazy letter in the mail that says she will not accept this from us and that they are a packaged deal, we need to stop judging her, and let her know if we can be a "whole" family. His stepdad is not our family and.never will be! He does not say two words to my husband when we go to visit! Why the hell did she ask what he wanted if she wanted to fight with him about it? Anyways, advice??? What do we say to my crazy MIL who I do not want to offend and I do want her to come for baby #2's birth?? She is very good at twisting our words around. .. *sigh*