My boyfriend picked a fight so he can cheat on me

I DESERVE BETTER!

So long story short, I seen a girl on my boyfriend’s Snapchat list. I asked him who she was. He told me no one important just a friend they sent snaps of the cat because she has a cat too. I pressed him about the issue again in text messages after he told me we needed to talk so I called him and he basically told me he doesn’t think this relationship is going to work because XYZ. So basically, he picked a fight to try to break up with me so he can continue talking to that girl. This happened on Monday fast forward to Friday. He met up with the girl and had unprotected sex with her. After he apologized to me and told me he regret it. I am so stressed. I’ve been crying since I found out every single day. I’m coming on here to ask for advice because I’m weak. I took him back and told him we’re not having sex until he gets tested. I know I shouldn’t have took him back, but I love him so And can’t imagine life without him. I’m truly devastated and heartbroken that he would do something so irresponsible like that. He’s a selfish individual and did not think about me once while making that decision I know I shouldn’t be with him again, but it’s so hard not to be what should I do?