My FMIL was fine until we got engaged too--turns out getting engaged was too much for her since I was not born Jewish--nevermind that I am converting (for HIM, not her--it's important to my FH and that our children be raised Jewish so that's my motivation). to her, I am going to be "faux" Jewish. You know I spent a lot of time being angry/resentful/etc. about the whole thing--FFIL is NO better, even more snobby if that's possible--and it's pointless. I discovered that in addition to their bias, they will complain and be unhappy with any and everything. You just have to do your best to distance yourself from the negativity and move one, easier said than done, I know. Hang in there!