<human>: So I've been sleeping with this dude for the past 2 months and have always known that he has had a girlfriend. I thought I was okay with it but recently it has really started to bother me. It's a long distance relationship so they aren't ever physically together, but I'm pretty sure that they spent Christmas/New Years together and he recently visited her but was texting me the whole time. Nothing along the lines of "I miss you" (but he did that over Christmas/New Years when we were apart for 2 weeks) but just silly pictures and such. 
Anyway, I have recently been starting to feel guilty about everything and am just realizing that I want more but I know that won't happen, and honestly I don't want more from him specifically.
It also seems like he's starting to become more controlling - every time I mention cutting my hair he never wants me to cut it shorter than a certain length, he texts multiple times if I don't respond right away, etc. 
We have great sex and I genuinely enjoy his company, but I know there's a limit to everything we do. We went to a movie once and he put a lot of distance between us and was upset when I ran into a friend there and genuinely made me feel like crap. 
I think I want to end the relationship but I'll have to be around him (we work together) for at least the next 6 months. How do I do this without making it awkward/uncomfortable?

Could you distill the essence of the text into 1-3 sentences?
<bot>: I want to break-up with my fwb who has a gf, but will have to be around him for at least 6 more months. How can I do this easily?