My(21m) girlfriend(20f) upset over vacation with friends

My current gf(20) and me (21) dumped me a few month ago but last month we started to get in touch and decided to get back together.

I will be taking a vacation with friends for 4 days. I offered her to attend but she decided not to due to the money problems. She will be taking another vacation however, more or less the same price in January and I think the main reason she declined the offer is that she is intimidated by my friends.

My friends are somewhat distant to her bes of the way she dumped me. I was a mess. I thought this could be a good occasion for her and my friends to spend some time.

Although I would have wished to have her with me I don't want to stop myself from spending time with my friends to not upset her. This has been a problem for us before the breakup so I don't want to get myself in the anti-social girlfriend pleaser position anymore.

I think I require some advice in the "is it a good idea to get back with an ex?" field as well. Thank you