Unless you're dating someone else. Or if you don't like him back, that would just lead him on. And might lead to a broken heart. That to be of your friend. If you do like him back. You've got absolutely nothing to worry about! Go ahead and have fun!
your boyfriend would be pissed... even if he says he won't be, he will deep down. I say talk to your boyfriend and ask if its alright to hang out with him... if he says yes, go on ahead, but don't accept his gift