ladies I need some advice. 
My fmil and my fi have been very close his whole life.  I came along and she does not hide the fact she does not care for me - and now that we are wedding planning she trys to make every little thing an issue and it's starting to cause major issues between her and my fi.  To the point where he got really upset last night and told me since him and I became serious seeing how his mom behaves towards me and some other people around me (like my family)  has made him not like her as much - really a heartbreaking statement.  
To summarize, she started out not liking me because we are so different.  She is a very religious, quite, and conservative woman from the Midwest who stayed home, had dinner on the table everynighy by 6, cleaned everyones room, did all the laundry etc etc.  I grew up back and forth between Miami and new York city so I'm not going to try and pretend I'm quite or super conservative.  I'm also an attorney and I love to cook but I'm not about to iron all my fi's shirts for him - that's what the dry cleaner is for.  (this is actually a huge issue for her - that I don't iron).  She's also called me and told me I should convert to Catholicism for her family - to which I Sao thanks but no thanks.  I'm okay with us being different, I don't need or want everyone to be like me - my sister is more like my fmil and we still have a fabulous relationship. 
The conversation last night started because she called my fi and said we needed to order two sets of wedding invitations because she refused to have her family receive invites with my fi's stepmoms name on them.  She has been married to his famther for over 20 years and is a wonderful woman, plus two sets of invites is expensive - I basically said that's not happening.  She then started yelling saying she guessed she could deal with it but that her daughters wedding two years ago was so much better and she already knew she would never have as good of a time at ours.  (they ordered two sets of invites for that wedding). There was more to it - she's mad my fi's brother (half-brother) is in the wedding and was yelling she knows that had to be my idea to make him a groomsmen and he's not a real brother because he's half and shouldnt be a part of it). That also upset my fi because they are brothers and talk.  Anyways I know this is an issue my fi should work out with his mom but I hate that he feels since weve been together he doesn't like his mom as much - I would never want to be the cause of something like that - family is the number one most important thing in my world.  Anyone have some advice of how I can try to make this better??                
                