My boyfriend, before he went out with me, previously liked a very attractive girl. He had a few options on girls to date, but in the end chose me. I've always not liked him talking to her because I guess I feel a little jelous, even though he tells me all the time that he loves me. However, he always texts her behind my back, when he gets texts from her, I'll ask him who it was and he will say "no one", he always tells her that she's attractive in her photos on fb when he posts them. Is this a sign he has had feelings for her the past 8 months we've been together?

This is one of those chicken and egg situations that we can't possibly answer.
Either you have been acting too jealous so he lies, or he lied first and that makes you jealous.
He chose you. Would you throw it all away by squashing his contacts with pretty exes and women in general?
I can remember such jealousy, so I'm not condemning you. There were mutual small jealousies in my case, and we kept a lid on each of ours. Most people have them to some extent. It's constant work in a healthy relationship to allow some little attractions with others without letting them get out of hand.

Talk to him. Tell him you want to start fresh, without snooping or being jealous, if he will keep it to a minimum. Be clear what that is.

Oh and may I add to that answer... when or if you do have a fresh start together tell him to cut it out telling her how attractive she is on fb, its demeaning you in front of millions on that site and making you feel insecure, why waste compliments on her when he can be telling you nice things about yourself.

He chose you, but he still likes her. Maybe they are just friends now, text buddies, Facebook pals, whatever. Doesn't mean he likes you any less, or her any more.

Some exes stay friends, so don't be so jealous, even though I can understand it. Tell him he doesn't have to lie about who he texts, or contacts on the Facebook thing. Then maybe you won't have to snoop.