WIBTA if I rejected my friend's request to bring his girlfriend to a hangout

Some context for this: my friend (male) has been dating his girlfriend for upwards of two years now. They really like each other and I'm happy for him. While I would never say this to him, I'm not a huge fan of her.

The times I've been around her, she's been pretty harsh to me and sometimes even mean to me. I'm unsure If she is like this to my friend wuen they are together. I've invited her to a few things because I'm the type of person who can talk and get along with everyone. During these times, I would third wheel hard because they were kind of just in their own world together. It got so bad that I would have to invite another friend just so I had someone to talk to.

The straw that broke the camel's back is when we went on a day trip to a big city. We were at a museum and I went to go sit down and I didn't tell them because I wasn't planning on going far. I tried to then text them to let them know I sat down, but there was no service. So, I went to the floor beneath and there was no service there. So I had to go all the way outside and across the street just to get service to let them know. They eventually made their way over to me. My friends girlfriend hit me and said something along the lines of "don't do that again," or something. Now, when I say hit, I don't mean she hurt me. It didn't hurt, but it wasn't just a slight nudge either.

Later in the day, my feet were hurting all day because the shoes I wore were too small. So, I was making a joke, but was kind of serious at the same time with my friend that my feet were getting blasted and she asks if I want to stop at a cvs or rite aid to get a bandaid for a potential blister. I said no and that I'll be alright and then she basically said "OK, then stop complaining," or she might have said "OK, suffer then." When we were walking from one place to another, I would often find they walking ahead or behind us, not really caring to talk with us and only really caring to talk with each other. On the train ride back home, they sat a bit further away from my friend and I (that they both like and know) and just talked amongst themselves.

As you can see, if I didn't invite my other friend I would've been the ultimate third wheel.

At that point, I promised myself to never invite her to anything again. Maybe I'm too soft. I typically like those kind of people, but that's because I talk shit back. However, I can't really do that with my friends girlfriend because he may get defensive of her.

Anyway, I invited my two friends (one of them has the gf I was just talking about) out to a Halloween event. My one friend asked if he could bring his girlfriend along (the one I just got done talking about). Would I be the asshole if I said no?

Thanks so much for reading this long post.