My 3 year old acting different around my fiance

Recently my fiancé & I got engaged so I figured our relationship would only get better but here lately things have not been the same. He’s acting like a different person recently we had a disagreement about my daughter breastfeeding still which I know she’s a little too old but I’ve been working on weaning her at her own pace it’s my choice & I know works best for her. So he went on to being passive aggressive, not talking & not eating. He didn’t eat anything for 3 days straight & held his pee for almost two days which I’ve never ever heard of someone doing that! He just laid in bed pretty much pouting. We’ve been off & on into it for two weeks straight. Then the other day my daughter was overly tired & didn’t want to finish her dinner. He yelled & cussed at her excessively which caused us to have an argument. Ever since then she’s not trusted him. Then the other morning she crawled into bed with us to & she was having a breastfeeding morning & he thought I was asleep when he for no reason than she was on the boob, which he doesn’t like, he smacked her hand which again caused a lot of tension between us & I could of swore he was also trying to push her off of me when I was asleep & when I woke all the way up it stopped. He won’t admit to it obviously. Then my daughter has been acting different as well. She’s been very moody lately. She’s woke up from her naps crying & screaming. Last night after I bathed her I took her to our bed to get her dressed & everything. I forgot my cellphone in the bathroom & told her I need to go grab it & I’ll be back. She started screaming when she thought I was leaving her in the room with him & I had to take her with me. I know he needs to go my child comes first but I wanted some other women’s opinions on this. Please no negative comments but criticism is ok because I feel like such a horrible mother & feel like I should have noticed something wrong a long time ago but they’ve got along until now & she loves him to death & calls him daddy because her real father isn’t involved in her life.

Edit: only one time that’s all & it’s been a while since they’ve been alone.