OPINIONS/ADVICE PLEASE 😔😩😡

How do I tell family to leave me the fuck alone? My family, one relative in particular (she's a distant cousin or aunt or something but I just call her Maricela), is extremely overbearing and makes me not want to take my son around her anymore. Last night we went over to her for dinner. My son, Mateo was really fussy when we arrived because he needed a nap after a long day out. I put my son down after nursing him and he fell asleep. I warned everyone to leave him alone so that he could get in a good nap (and in the meantime I could eat dinner). I swear as soon as Mateo started stirring a little (not even twenty minutes later) Maricela picks him up. Like didn't I say leave him alone? He wasn't even fully awake, he would have fallen back asleep! I didn't get to finish my dinner because he got fussy again and wanted to fall back asleep. I let that one slide... Later on, Mateo started crying while I was in the restroom. It was time to nurse him, but I wasn't really worried because I knew Derek (my fiancé, Mateo's dad) could handle it and keep him calm until I was done, so I took my time. When I come out of the restroom a couple minutes later, Mateo is still crying and is getting more and more upset 🤔 I come out to see my fiancé asking my aunt for the baby so he could calm him down, but she refuses to give him to Derek and walks away. I chase her down, ask her for my child and she ignores me. I told her twice to give him to me! Her phone starts ringing and she fumbles to answer it while still holding my screaming child. I was livid. Seriously bitch give me my child!!! 😡😤😡😤 Wtf is wrong with her? My dad finally took him from her and gave him to me. She wants to see and be around him all the time, but this kind of shit keeps happening. There has been other times when Mateo is crying his eyes out and she won't give him to Derek, instead she'll wake me up out of a dead sleep or go knocking on the bathroom door. Like hello?!? Derek is Mateo's daddy, he can calm him down just as much as I can. Her attitude is starting to rub off on my my mom too. I don't understand why they feel Derek and I cannot take care of our own son.