Did I handle my mom in law badly?

Actually, she is not your mom in law, as you are not married. Second, If your boyfriend doesn't side with you then you have a bigger problem than you realize. I had a mother in law (i was married) that had to be in control of everything too. She eventually ended our marriage. There were other problems, but she had to know everything and control even more. You were not wrong to state your opinion. My advice is to stay away from the person that you know gossips about everything. AVOID them. It is your right to have your children around people who are positive and not filled with gossip and negativity directed towards his mother. Smacking his hand is not child abuse. Here in NC spanking (corporal punishment) is legal.. I don't believe in spanking a 2 year old, but a gentle hand spank to say no, is fine. If Shanna is causing drama, then don't go over to her house, don't go to parties where she is at. Your son is only 2. He won't miss the party. Get him in a play date group. Make friends with other moms at church or at places you attend and arrange play dates with other kids. You are also correct about not letting her give any medication to your child, much less a baby. Breastfed babies are generally fatter babies. All 3 of mine were very plump and are now fine and normal weights. A child under 2 should never be placed on a diet or have limitations of a diet put on them. They need the fat and iron for brain development. What kind of person wants to place a baby on a diet? That is just insane. As I said. She is not your mother in law, just your boyfriends mom. She has no say so in what you do to your baby. Even if you were married to the father, she still has no say. BUT I would definitely think twice about a man that sides with his momma against you. It is a warning sign of things to come.