Confused

So my daughter was born 3 days before my boyfriends sister baby. I have a girl , she has a boy. We decided to do a half birthday party pebbles and bam bam themed . That didn’t work out , so we kind of was just going to do our own thing. Today i was talking with my boyfriend I said well I’m still doing something even if it’s a picnic. I need to make things clear that I won’t be doing joint things all the time . I’m not doing a joint christening,joint birthday party none of that. His family is very dominant and I have my own brain and this is my child. Earlier I let him

Know that he should Check with his sister to make sure the picnic isn’t on the same day so if she was doing something he wouldn’t miss his nephews party. So his sister texted me and said he said you want to do a joint event and I’m doing baby shark. That theme isn’t my favorite but I’ll do anything for my daughter .So she send me an outfit which was cute it’s Gucci. In my head even though I can afford it why am I putting that on my child for one day and wasting all that money. So I said I might do a Moschino outfit for her , it’s very known and way cheaper . He goes off and says if you not going to go with the theme don’t do it . They have to wear the same outfit .He yells and curses at me and says he doesn’t want to speak to me right now and hangs up the phone.