I need some advice!!!

I'm 36wks pregnant, about to have my husband's first child (a boy, no less!! ☺️☺️). I have 2 from a previous marriage. Anyway, his mother completely blew up on me for no reason, a little over a week ago. She's been emotional bc her mother just passed so I understand that she's grieving. One stage of grief is anger; I get it... But she went off on me like I was some petulant child, chastising me for sth with which I had absolutely no doing... Well, she has yet to apologize and is now ignoring me. I don't understand this behavior. It's terribly upsetting. I've literally cried my eyes out this past week bc of being so hurt. It's even created a strain bt my husband and myself; not bc he sides with his mother but bc I feel horrible that he's to a point that he's not going to have her near our son until she sets things straight. She's creating this rift but I'm the one that feels bad! How messed up is that?! This isn't at all how I expected things to be. I moved to be with my husband to a place I had no family. All I ever wanted was to be an extension of their family and she's completely ruining it for me. I love his father to death, but his mother is ruining it for him too. I'm not going to want to go over to their house just to undoubtedly feel tension.... Well, our son will be here soon and I have horrible anxiety about how things will go. If she doesn't come around, I'm afraid that I'll just feel like writing her off entirely. I don't want to come off as petty, but her actions and words were inexcusable. How is this going to work with a new baby? I know she'll expect to see him but I don't want to have to deal with her if she's not going to own up to her mistakes. What do I do?
*My husband has been my hero throughout this whole situation. Reassuring me that we're a united front and that his mother's feelings are not his #1 priority. Mine are. And his family (myself and the kids) come first.