Sons first birthday possibly be ruined


So I’m posting because I’m really torn and could use advice my son will be turning 1 July 24th it’s a huge deal for me considering he’s my only child and I’m a single mom however I’m very close with my family and they are huge part in my sons life and I’ve been planning his birthday for months I’ve been very excited about it well now my older brother who I’m close to and who’s amazing uncle to my son is dating someone who use to kinda be my friend until she was rude to me a number of times she kinda says rude stuff a lot and is very mouthy and judge mental kinda person I honestly don’t like her but I’m happy for my brother to have a gf if he’s happy anyways my family goes camping a ton we all have very fancy loaded toy haulers,travel trailers, motor homes and we ride quads at the coast a lot well anyways my entire family especially my mom all love my brothers gf because she’s never treated them or acted the way she has with me with them well now she’s able to get tome off work to go camping July 19-24 this is a 4 hour sometimes 5 hour drive and also my sons birthday well so now my parents want me to spend his birthday on the dunes at the coast because “she” has this time off to go camping now is it just me or does it seem like that’s coming before my sons birthday and that his birthday isn’t that important now and this is more important I honestly don’t know how much fun it’ll be for my son they claim we are going to go drive out and do other things like see sea lions and camp right next to the beach for my son to enjoy activities but our beach is cold and windy so I’m not sure how that’ll go he’s never been camping yet and I don’t want to get there and be upset and feel like no one cares about his birthday what should I do? Tell them no I don’t want to do his birthday there or say yes and go and maybe have a good time or a horrible time I’ve already decided if I say yes condition would be I still want to do all his decorations and will need to make the cake there in the toy hauler because I don’t want to bake it put it in the fridge and give it to him days later and we will need to stay longer because I won’t make him be stuck in the car all day for his actual birthday but I’m just torn and are they being selfish or am I over thinking it all thanks