Yeah, it does sound a lot like his mom is freaking out. This is a really wierd thing to happen.. it seems like his mom was OK with everything until she got up to the point where she was at the jeweler's picking out a stone for his engagement ring... has he ever been/is he a "momma's boy?" You should probably talk to your fiancee, and have him have a sit-down with his mom. I'm really sorry this is affecting you... in-laws can be a pain to deal with! Perhaps, after your fiancee talks to her, you could talk to her (if you feel comfortable). You are going to be in the family soon, and you need to make sure that the lines of communication are very very open, even if she feels she doesn't "like" you. Good luck!
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Sage knows our mythic history, King Arthur's and Sir Caradoc's
She answers hard acrostics, has a pretty taste for paradox
She quotes in elegiacs all the crimes of Heliogabalus
In conics she can floor peculiarities parabolous
-C'hi