Over reacting?

So my boyfriend has a best friend that hes known for a few years. She is really nice and ive met her a couple of times. She has a boyfriend but they constantly tell eachother they love eachother ( in a friend way he says) and have nicknames for eachother. And are always talking about things theyve done. Theyve even slept in the same bed together but they swear they had no intercourse. My boyfriend used to have the biggest crush on her. Biggest. I just have a feeling that my boyfriend still may have feelings for her. Though he swears he doesnt bc "shes had her chance and blew it" as he says. Though i find out that shes had feelings for him as well. I just dont know how i feel about them always hanging out and stuff... Am i over reacting?