Should I worry about his female co-worker?

My boyfriend and I have been together for over two years and we live together. However, he has a female co-worker that I have a bad feeling about, which stems from a few things. Before I met her, he would always talk about how everyone at work thinks she is so hot, "except for" him, and how she thinks she is a princess and God's gift to the world. He basically painted a picture that she was annoying as was how everyone in his work place including clients are in awe over her. The first time I met her was at a happy hour where she was being very flirty with everyone and even rubbed up on my bf's butt in front of me and then put her hand on top of his while ordering a drink at the bar. The next day my boyfriend told her about what she did and she apologized to him, also asking for my number so she could do the same to me. A few months later when I saw her again she apologized profusely, so I thought no harm done.

She lives in the same neighborhood as us and ever since my boyfriend and I moved in together they have hung out (gone drinking) almost on a weekly basis with out me. I was invited once, but after getting angry at my boyfriend for something completely unrelated, he has said that he won't ever take me around his co-workers again (which is a lie, he really just means her). They stay out very late, sometimes to 3/4 AM, which I feel is disrespectful to me. He has lied a few times about meeting up with her and he goes back and forth between being friends with her and him saying he can't stand her. I have seen flirty texts between them, calling each other handsome and gorgeous; her telling him she likes it best when it is just the two of them out together; and her referencing something about hoping it would rain that night (which I took as a sexual innuendo). Her sister, his cousin, and his friend have all commented on their relationship saying that it is weird or asking if they're sleeping together, to which they both say no, just friends. He cheated on me once before, early on in our relationship and we broke up. Since we got back together everything has been great, but now I am obviously feeling worried again. I don't flirt with any of my guy friends or go out with them alone out of respect for my boyfriend. He knows how I feel about the whole situation and often makes little jokes and comments to me about her just to make me angry but then tries to say that I shouldn't be worried or jealous.

My brothers always used to say that guys don't routinely hang out alone with another woman (if they're involved in a relationship) unless something is going on. Is this potential cheating or am I worried over nothing?
Should I worry about his female co-worker?
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