You don't know anything about the guy at work and you'd be a fool to let a good boyfriend go- for the sake of some physical fling. Physical attraction is important- but not at all enough to build a relationship on. This man's character doesn't promise much if he was flirting with you& sending you sexy msgs while he was still with his girlfriend. If he cheated on her emotionally, why wouldn't he do that to you? THINK. Use yr head& not just your hormones.
Be honest with yourself and yr boyfriend; that's the least he deserves. Of course he was upset; wouldn't you have been if he'd been texting some other girl& flirting behind yr back? Get real.
THINK. If you give up a nice man for a man who plays around, YOU will be the one to regret it- and yr boyfriend will be unlikely to take you back.
If you're truly bored/ unhappy with your boyfriend, be honest and tell him and end things amicably. That way you can still be friends. He will respect you- and most importantly YOU will respect yourself. But messing around on him& cheapening yourself isn't the answer.
If you break up with your boyfriend, give yourself time before you go out with this new guy- till you know more about him. If he doesn't want a serious relationship and you get more attached to him, you'll only end up getting hurt. So be cautious.
As for pregnancy, if you haven't had unprotected sex, the chances are slim but it's possible. You should go to a gynecologist and get checked out. It might be a benign cyst that needs to be seen to; that can delay the period. If you are pregnant, then you can still get an abortion if that's what you want (if you're not gonna settle down with yr boyfriend& don't wish to be a single parent) or you can give the baby up for adoption. It's your choice but you have to go soon; otherwise it gets too late for an abortion.
Once you find out, you have to be honest with your boyfriend about what it is you want to do. The more honest you are, the less you'll mess up yr life. Good luck.