I have avoided my fiance's girlfriend for several years now, because I think she likes me and it makes me feel uncomfortable. The problem is that there is an event coming up this year that we both were invited to, what should I do?

So you have told your girlfriend about it and that it bothers you?

But so? She likes you, if you just don't give her attention or the wrong idea, you can't run away from any and everyone that may like you.

She should never stop you or your girlfriend doing the things you like to do.

Hey

So you THINK she likes you?
Its never good to think things like that, she could just be a very flirty girl or feel really at ease with you because you are with her best friend.
Have you spoken with her about how she is making you feel?
As simple hey step back your making me feel a bit odd here thanks.

And even if she likes you.. that is her issue. You! Do not need pay for that.
I understand it will make you feel a bit off.

But honestly she likes you.. so what? Just because she likes does not mean you guys are going to go to bed together,

Just go to the event with your girlfriend with your heads up high and proud.

Also it seems to me your girlfriend knows about this and she does not seem to care
So why let it bother you?

Have you spoken with your girl about this?

I wouldn't let this get in the way of anything

Be honest with her friend and your girl tell them all how this is making you feel
And how you don't like it.

Simple

https://www.askmehelpdesk.com/marriage/think-wifes-friend-likes-me-how-can-sure-209084.html

No need to be uncomfortable, just be dignified and respectful as you would any body else when you are in public. Be an interesting conversion to have why she acts the way she does, or asks the questions she does of you.

But be sure your girl friend understands and knows your concern