My MIL is driving me crazy! (Vent&Long)

I'm not really sure how to deal with my MIL anymore since i've become pregnant shes been all up in my business,got mad because i didnt let her go to the gender u/s (i didnt let my mom go either) but she still got mad. I feel like im having to play nice with her all the time because when i go over to her house she always points out how i've gained weight or that i've deff been eating and now its getting to my fiance he's starting to get mad when he thinks im eating to much.

Also, she gets mad because i refuse to let my 20 month old son spend the night at her house (he's not related to her in any way,he's not my fiances bio son). I dont let my child stay with anyone because i simply cant sleep and go insane without him there at night, i have no problem with her watching him during the day but i cant take a night away from my child i drive everyone nuts. But she keeps trying to push me into it and now she's started calling my son Aidan a bastard and saying how she thinks my fiance and i just have to be married before the baby is born. It makes me think that she dosnt think aidan is as good of a child because i wasn't married to his father when he was born. But i refuse to get married to him until he can provide insurance for me and my childern. It's not the kids insurance i would be worried about because they would have medicade (sp?) but im going to need insurance so im not getting married until it can be provided so i can stay on my moms insurance until im 19.

Im very very tired of her trying to push herself on me, i've tried to be polite when asking her to back off but im just about ready to tell her point blank to back off,i had to tell my mother that when my son was born,and personally i have no problems telling her to back off but i havnt because of my fiance. But with my MIL she is taking care of her oldest daughters 3 childern and i dont know if she thinks because im younger that i cant take care of kids that she'll need to do it for me or what but regardless (sp?) of my age i believe i am a very good mother. My son is well taken care of and always happy.

Im just not sure how to deal with her anymore..any advice?

Sorry about the rambling (sp?) and any spelling errors

You're pregnant, you're supposed to eat. How the hell can she comment on that and how can your boyfriend agree with her. They're both nuts in that aspect. I would tell her to back off.

i know that and you know that but they are pig headed! They think that i shouldnt be eating this much and blah blah blah its not like im stuffing my mouth with junk food or anything i eat like i normally would im just tired of hearing that im fat it really makes me mad.