Really need advice. Please read

Soo ima try to make this story as short as possible if I can. So my bf and I been together for 2 years. He first year of our relationship was pretty rough. His mom was battling cancer and sadly she did not make it. She passed away about 6months into our relationship. This destroyed my bf. Soon after I noticed our relationship started to change. I noticed he started pushing me away. I tried my hardest to be there for him. Things between us towards the end of our first year got pretty bad. Lots of arguing. So we decided to end things while we still can. We didn’t want to end things hating each other so we broke up. We thought it was the best thing to do. So we were broken up for about 3ish week. No contact. Then he comes back to me telling me how much he misses me and how things are going to be different.

He said he didn’t realize what he had until he lost me. So anyways fast forward to where we got back together. He did tell me that he did go out on one date with a girl during our break up. But nothing happen between them. This bothered me a little bit but I felt like I couldn’t get mad because we where broken up. So fast forward a whole year till now. Things are great. On my birthday he took me on a trip to Vegas. On our trip we happen to run into some of his friends. And during that run in I noticed this girl in this group and I got this vibe between her and my bf. It felt like an awkward vibe between the two. The next day I bring her up and ask “hey did u and Michelle has a thing before?” And he was like “no, there’s nothing between us she’s just a friend of the group” and I was ok. But I couldn’t get that gut feeling something was there. So I ignore it. Then fast forward to last night. We were hanging out watching movies and just random thought came to my head so I ask him. “Hey I know this is the past but I was just thinking when we where broken up did u hook up with that girl u went out with?” And he was like “who Michelle? Nothing happen between us. We just hung out once”. I never knew Michele was that girl. I always thought it was just a random girl. Then I said “wait it was Michele? U never told me this. I specifically asked you about her a month ago and u didn’t tell me anything” and he was like “well I didn’t think there was anything to tell u. There was nothing between us. We hung out once. She didn’t like me”. So then I asked “wait u liked her? I always thought it was a random girl u found cute and decided to ask her out. But now u telling me u had a thing for her” and he was like “look I’m with u. Idk why ur talking about her. She didn’t like me.” So then I asked him “wait. Did anything happen between u two while we were together?” And he was like “no. I only texted her for like 3 days during our break up and hung out with her once. Nothing happened.” Soo then thoughts started running thru my mind. Thoughts like I’m his second choice. I can’t get this thought out of my mind. I told him that I feel like a second choice. And he said “wtf no you were my first choice. Don’t feel like that. I wanted u back I realized I had the best thing in front of me and I let her go. So that’s why I tried so hard to get u back”.

Idk ladies. This thought of feeling like a second choice is running thru my head. Like this girl wasn’t a random he liked her and tried to pursue her. What if she did like him back. I can’t help the thought that if they did work out he wouldn’t want me back. I feel like things didn’t work out between them so he decided to come back to me. I just feel like a second choice. I know this situation was so long ago but finding this out now just makes me feel worse.

Any advice?