Uninvited wedding guest

Hi, this is my first time asking for advice on a forum so I’m a little nervous lol.
I’ve recently found myself in a pickle. My wedding is in March and our invitations have been out for a few weeks now. One of my bridesmaids decided to take charge and start planning the bachelorette party without notifying or getting any input from my MOH which led my MOH to be disappointed cause she wanted to plan it.
Now, I love my MOH but she is a bit of procrastinator so I’m happy my other bridesmaid stepped in to help but I was so surprised she didn’t communicate at all with my MOH. To make things a little more complicated my bridesmaid started to invite guests without asking me which got me worried cause I didn’t want anyone to get invited who wasn’t invited to the wedding but when she told me who she invited I thought phew it’s all people who are invited to the wedding. That is until the following week...we were talking about the bachelorette party and she mentioned a friend was coming that I didn’t know about and that wasn’t invited to the wedding. I like this girl a lot but we haven’t really hung out much in 3 years and my fiancé and I are real limited to who we can invite because of the capacity of the venue where the wedding will be held. So what should I do? Should I explain to this friend what happened? Or should I just invite her to the wedding g and hope we do t have too many people? Please help.