I am looking for some advice in how to deal with my mum's partner and his attitude towards my son, currently 4 months. They've been together for around 10 years, but he's only just moved in with my mum a couple of months ago, due to having children of his own. Despite knowing him for this long, I don't feel I know him very well, as he was always around on a weekend basis, mainly every other weekend or once a month. I've never really felt that comfortable around him because of the way he is with my mum; he's very "touchy-feely", not affectionate in my opinion, just inappropriate. He's extremely passive aggressive and patronising. When my son was 7 weeks old, we were round at my mum's for dinner, and he was sat in his car seat on the floor next to my mum, he couldn't see me, and as a breastfed baby he was feeding a lot. He started to cry and my mum went to pick him up, only for her partner to turn to her tell her not to, "because he has to learn". I jumped straight in and told him not to be ridiculous, he was 7 WEEKS OLD!!!
Fast forward and similar things have happened. Yesterday though, we were round at my mum's again for dinner, and my husband was cradling my son as it was time for bed, he started to cry and my mum's partner got up and took him off my husband. It's not easy in those situations to argue against something like that, for the sake of the safety of the baby's health, so he felt he just had to surrender. (We already know that he views us as just "kids" as he's implied several times, despite the fact we're both 23 and have careers). At first he held him in the same room and rocked him, but he carried on crying. He then went upstairs, and we both assumed it was just for a walk and he would be back soon, but he was gone for around 5 minutes. My husband wondered where he was and went up to find him stood in my mum's bedroom, in pitch-black darkness, but had heard my son screaming on his way up the stairs, he also thinks it could have been a bit muffled. When he went into the room, my son was still crying and screaming, and he said to my mum's partner that he'd have another go at calming him down. My mum's partner didn't say anything and handed him back to my husband.
It wasn't until we got home that I found out any of this, and I don't know what to think. My husband was pacing up and down the kitchen, as he just found it very odd that someone would take someone else's baby out of the room for a pro-longed period of time. I managed to calm him down, but I'm worried. He calls himself "granddad" which I absolutely despise. I don't even consider him my own step-dad. I have no idea how to go about this at all, I don't trust him with my son anyway because of what I've seen so far, and it would kill my mum to deny her of looking after her grandson, but I just can't deal with the fact her partner will be there all the time.
Please, any advice at all.