Married 23 yrs in love with my girlfriend. What to do?

You want to spend the rest of your life with her... how does she feel about this? The same way or no?

You better be real sure about what you're doing. Sounds to me like you're just obsessed about being with her.

I would have to separate from my wife first I believe, before my girlfriend would be with me full time, but my wife and I party with almost every weekend. The big question is I guess if my friend feels the same way for sure.. She says she does love me and her feelings are driving her insane
Also but won't act because I am a married man and I wouldn't respect her if she would anyway.. So we drive each other crazy. My wife knows I flirt a lot with her but may now know its more

This is lust or perhaps a mid life crisis, and love real love is grown from years of being together and working though problems.

I would say you will ruin your life, but if you are trying to cheat on your wife now, you have already ruined hers.
And you will most likely see this come and harm you after enough years pass.

Why not get counseling, stop seeing this other person and try to make it work with your wife

So you and this friend party with your wife and carry on behind her back? Ask your wife if you can have her as a play mate, or if she can't, maybe she could give you a separation so you can be with your friends and act out your hot animal lust together.

What are you afraid your wife will cut your thing off or something? Talk to your wife and see what she says... or does!!