I apologize if this is lengthy...
I really need some advice about  dealing with my FMIL and how overbearing she can be. Let me preface  this by saying I appreciate how excited she is about our wedding but  things are quickly spiraliing out of control and I don't know what to do  without hurting feelings.
Here is the backstory - my fiance and I  have been together almost 7 years, we're both very close to both our  families. He just proposed in October so we don't even have a date or  venue yet and we're just trying to enjoy the holidays this year before  the craziness starts. The only thing we've planned is the bridal party.  He has a twin sister and over the past 7 years we've become like sisters  ourselves so I asked her to be MOH. Well, his mom seems to  now think  she is MOH! She has begun planning everything from the bridal shower to  the bachelorette party with no input from anyone. It's a sweet gesture,  but again - we don't even have a date! Also - I think she is living  vicariously through me and my MOH (her daughter) because she didn't have  a wedding herself. Everything she is planning is SO not me (really  tacky invitations, male strippers - seriously.) and I am in need of a  way to let her down gently. We already told her she can be in charge of  making and sending Save the Dates (she runs some greeting card website  that is not my taste at all but we knew this meant something to her so  we told her when the time is right she can create and send those), but  she is really going out of control with all these other plans.
My  other 5 BMs also know me very, very well (2 sisters, a cousin and 2  friends from childhood). I want them to plan the shower and Bachelorette  along with my MOH and I really need my FMIL to stay out of the planning  of those things. She can be very overgearing and one step in the wrong  direction (aka not going along with EVERYTHING she wants) causes her to  become (for lack of a better word) downright nasty. She's amazing and  sweet 99% of the time, but the few times I have disagreed with her were  brutal and I see some unpleasantness already coming out if I don't jump  for joy over her ideas related to the wedding. My Fiance understands and  he has tried to talk to her, but again - she gets nasty. It's her way  of the highway. My MOH knows me well and knows what I want but she has  been taught to basically go along with whatever her mom wants or suffer  the wrath as well. I don't know what to do! Any advice is appreciated. I  just want my girls to plan these events because they are all looking  forwrad to it so much and I need my FMIL to take a step back. Thanks for  any help ladies!