how do you deal?

with insecurity. I've been with my boyfriend for a little over a year, and I try my hardest to not have insecurity issues, but he's a battle rapper, and he's starting to get really good like he could be pretty famous soon, and I don't know how I'm going to deal with all the females being around him. I can't go with him to his battles because I'm not 21 yet, and so I'm jus scared he's going to find someone better and leave me. I'm currently 18.5 weeks pregnant with his child, but I still worry. I know he loves me, but maybe it's just the hormones making my insecurity worse, but he says he wants to make a music video and he wants girls in it and I just ugh it makes me so mad every time he brings it up. please tell me how to get over this.