My mother in law is driving me insane!!!!!?

I have lived with MIL for almost 2 years and it wasnt this bad at first. We were supposed to have moved out a year ago but my fiance lost his job and now has to wait till the week after july 4th to start the new one. Every since I had my baby she has been telling me what to do when it comes to raising him. At first I didnt care, but now its overwhelming. We have NOWHERE to go right now so Im just gonna have to tough it out but she literally told my fiance last night that we arent fit to be parents! Her son, my fiance did every drug for a few years then looked in the mirror and saw he had a problem and straightened out. Her daughter has been doing drugs since she was 13 and now she sells them! She thinks we need to lay off a little bit. When he was born, I was so scared he was going to get sick so noone other than MIL was alowed to hold him till he was 3 months old. Only because if we let one person hold him, everyone would want a turn and it wouldnt have been good for him to be passed around by 30 people. Now she wont shut up about the food thing. She presured us into giving him baby oatmeal at 3 months, we waited till he was 4 1/2 months and it turns out he was allergic. We knew it after the first time, but MIL didnt believe me. She almost kicked us out when I told her that we wouldnt be giving him anymore. Now, she keeps trying to sneak him abserd food like whole t-bone steaks so he can knaw on it, (teething but no teeth yet), cheetos puffs (full of preservatives) And she buy these pouch things which normally I wouldnt care, cause they are organic, but she HAS to get the kind with atleast 3 diff kinds of fruit that hes never had before! I keep telling her that I dont know if he would be allergic to certain fruits, my fiance is allergic to kiwi and mango. And if we feed him a pouch thing and he gets a reaction, we wont know what it was that caused it since there were so many types of fruit in one pouch. I told her last week that I do not want him eating cheetos puffs cause its junk and today she went ahead and bought a bag and tried to sneak him one! Like I said, we have nowhere to go or I would just leave. All we have to do is wait for this job to come through so we can see his schedule and I can get a job. I was just wondering if anyone was going or went through this and how you handeled it??!!