Is it normal to be jealous of your friend's boyfriend?

She's like my oldest friend and kinda my first love. When we were young we kinda dated, if you could even call it that. There was a lot of making-out and sleep-overs(we literally thought that "sleeping together" was sex...we were young ok)Anyway, we decided to break it off and never spoke of it again.
Anyway, we've always had a really close relationship. Like, if we were hanging out, she'd like sit on my lap, or lye on my chest. Our friends never really say anything because that's the way we've always been, closer than most people, even closer than she was with her boyfriend.
Now, she broke up with her bf, he broke her heart...and I thought I would get another chance, but then they got back together. So any time I see them together, I get sooo jealous. But anytime he tries to put his arm around her or tries to get intimate with her when I'm around, she pulls away, now maybe she's like that with him all the time. He's a really nice guy(bar the fact that he broke her heart) I'll never forgive him for what he did, but he can still try to make up for it. Then anytime we say goodbye she gives me a really long hug, like it's the last time she'll ever see me again.
So I guess what I'm asking is:
is it normal to be jealous of your best friend's BF?