Birthday Party vent

Laura
A little background. Me and my in laws don't get along at all. My side of the family and my husband's family have never been around each other. Initially we were going to just have one big party with both side. It just seemed smarter since we live on opposite sides of the country and we are flying out to do this since my husband's great grandmother can't travel and she's very important to all of us. Well eventually the stress of it just made me decide to do two parties instead (my mom was paying for a bulk of it and my MIL kept insisting we invite extra people. Somewhere around 40). So I have planned the party with my family and my husband is military and last minute they said they aren't going to let him go so I'm going by myself. I told my MIL she could plan something for my son's birthday if she wanted to but I wasn't paying for two elaborate parties. 
Where my rant begins is she hasn't checked in with me at all during this party. My son has allergies she doesn't know about because she never calls or anything. I texted her about his nap schedule and what time was best to have it and she got mad that I was trying to overstep I guess. But the party is for my son I kind of feel like to some extent she should discuss things with me as far as what I want and don't want for him and the reality is she doesn't even know anything about my son. She won't tell me what's going on or anything
And on top of that she says since she hasnt seen him in 8 months that he should stay overnight with her. That's just not a reality because I'll be staying two hours away and I just can't do that to myself. I rarely even leave my husband alone with my son for an hour. Am I overreacting about this whole party thing? 
Him staying overnight I just can't do. I'm overly protective and have severe separation anxiety with him (comes from my first son passing). She thinks I'm trying to keep him away from her though. 
Sorry for the long post lol. Vent over 😊