<human>: Can you summarize the given text in a few sentences?

So me and my FWB decided to be in a commited relationship (the 13th of last month). We've been talking for a year and a half. I'm 20f and he's 25. The age difference has never been an issue because I'm fairly mature. It only ever matters when we try to go to 21+ places. Anywho, I know about all of his past sexual history. I know some stuff I can't hold against him because we were never in a commited relationship. Yesterday we went out and I was joking with him about how all of the other chicks he's been with have been less than attractive (probably didn't help that we were drinking). He showed me this picture of a girl he was with and I honestly didn't believe him considering his history with other chicks. I asked him when he was with her he said 2 years ago. Then I asked him how long has it just been us two together (monogamous) and he didn't answer me. I asked again today and he said basically since the 8th of December. I don't know why that kind of crushed me. I've been with only one other guy since we started having sex with each other. I told him about that today and he acted so crushed. 

He was devastated about my one guy versus his how many ever girls. I've forgiven him for everything he's done. We're in love and don't plan on breaking up but I feel like I'm going to have trust issues. It's already in the back of my mind. He lost it before and then gained it back. I don't want to call it quits. I'm just really fucking confused.
<bot>: decided to be in a monogamous relationship with my FWB we both are in love. Found out about some stuff he did before we were officially a couple and I'm afraid I'll have trust issues.