Afraid boyfriend is cheating? Help please.

So ive been with this guy for 3 years now, and we're expecting our first child. (I'm currently 6 months.) A little light on our relationship; In the past, he has cheated twice between being together 4 months to a year. Not physically, as far as i know, but texts and pictures and such. When I had confronted him both times, he denied it, although i had proof right in his face. We had our spat, and i've let it go. (Don't tell me im stupid, i love this guy.) After that, everything has been great and all that mushy stuff. Until recently, he got a new job about 2 months ago. There is this girl that he works with that he seems to have become very attracted to. And i'll explain why I think that.
-Every time he works with her, he comes home and tells me all of the hilarious things she did while at work and goes on and on until I get irritated to the point i tell him to shut up.
-At his Christmas party, he was looking at her EVERY 5 MINUTES (not exaggerating) and when i would ask him about it, he would say he was looking to see who was there. (When she was the only person other than myself that he talked to the entire party.
-My friends go bowling where he works and tell me that they're too close for comfort.
-He looks up her boyfriend on facebook. <--- this is the one that really bothers me because i don't understand it. I was on his phone trying to look my friend up and her boyfriend came up 3 times.
I've tried talking to him about getting a new and better job, he absolutely refuses. He's also starting to become distant which is very unlike him because he's the clingy type.
Now, everyone is telling me to sit him down and talk about it, but as i said before, he will deny it because i know him. He told me he lies about things like that because he's scared i'm going to leave him.
Please give me some advice. I've been depressed for the past 2 weeks and i'm so tired of it.

Love is not enough to keep you happy with this one. Sadly, and because he's never had to face negative consequences for his deplorable monogamy skills, he's doing it again.

He broke your trust once, which is justifiable on your part, and you're having doubts about him. You are questioning his relationships with other people because he emotionally cheated before. Unfortunately, it looks as if the relationship between you two is dead, because the trust is not there. He might be cheating, he might not be. But you won't know until you find solid evidence...like last time. Listen to your head this time around, not your heart. You said you love him, but wakeup is right. This love isn't enough.