I was in a ery, very similar situation to yours. Had a lass who I was friends with for 10+years. Had made a drunken pass early on in our friendship but was laughed off. Stayed good friends, then a few years ago after meeting a lass in Albania who came over to visit, then went home, we ended up getting together. I had liked her for years and it had become a bit of a joke in our group about when we would eventually get together but it didnt happen till after the Albanian went home- jealousy maybe? It acted as some sort of catalyst somehow I guess.
Was a bit strange at first being a couple as we knew each other so well but still had a lot of fun firsts to do- was also a laugh seeing the look on folks faces when we told them we were actually together!
7 years later we’re married with 2 kids and still happy (most of the time..) I had written out the story in a lot more
detail there but thought a more concise version would be better.
Have a coupla glasses of wine together, just enough for Dutch Courage but not so much that she thinks you’re pissed, try and steer the conversations round to relationships, and tell her how you feel but with a get out if she’s not happy bout the idea- you never know-she might feel the same, if not, at least you know and can get on with being friends still..
Having been in the same situation I’ll keep my fingers crossed for you
Let us know how you get on!