She hasn't rejected you. She knows having something with you would be wrong, so she's diverted herself elsewhere.
She presumably feels bad about the kissing, etc.
She previously said 'no way' as you are her friend's husband.
I imagine part of what you like about her is her personality. She's just being practical right now.
You were not free to be loved. You have a wife. Her friend.
If you had been free and she'd refused you, that would be rejection.
This isn't that. You weren't free and she still couldn't help herself and kissed you, BUT she knew this was wrong so has stopped herself.
You should be grateful to her as the devastation an affair would bring would have hurt those close to you very badly.
I know that doesn't stop your feelings, though. I'm afraid you're just going to have to nurse yourself through this. And I would seriously suggest maybe some private counselling. You need to sort out where you are and what you want and what your family deserves.
Or you just grieve your lost love and cry at night for that perfect person and suck it up. As many of us have done. You just carry them somewhere in your heart.
And you look to all the good in your wife, and everything that you married her for. And you build on that. I don't know about your relationship though. The alternative is you find this too devastating and you split the family up. But you won't get the friend now. You wouldn't ever have, because she wouldn't hurt her friend (your wife) like that.
Personally I think you should stay put and work on your marriage. If you don't cope well with rejection, you won't like divorce.
I'm sorry that my advice is 'cry secretly at night until it dies down'. But that's how it is 💐