Okay I need some advice!

Chloe
So my fiancé and I are getting married in June but it's got to the point where I'm dreading it, his mother has tried splitting is up several times she's sent me messages under blocked numbers saying he's been cheating on me and she even called him a rape child in an argument she has been so rude and disrespectful to me and I've always tried to not bite back. Me and my partner always argue about her he is now inviting her to our wedding which has caused a few of our guests to not come because of how much of a horrible person she is very two faced and I've got to the point where I'd rather cancel the wedding and not marry him because even hearing her name makes me feel sick and fills me with dread I don't know what to do as all he sees is that she is trying not to make a mends .. All she has done was  give him money to help buy a new phone and I just don't get it we are very good friends with her ex as he has helped us out so much and always has time for us which is the opposite to her, she sent him death threats and told him to drop dead and other extremely horrible things and all my partner sees is that she is making a mends ... What do I do ? :( do I marry him? I feel like utter crap I don't want to make him choose between me or his mother it's so unfair but what else do I do :(