Relationship advice?

So my bf and I are about to be 2 years in a week. So the first year was really rough on us. His mom passed away and this really put a toll on him. Which I understand. We argued a lot towards the end of our first year. So we decided to end things. We were broken up for about a month. No contact.

So when we first got together I knew he wasn’t fully over his ex. But he always claimed he was. He hated her. Things didn’t end well between them.

During the break up he went out with a girl once. He told me this when we got back together. He said nothing happen between them.

So now fast forward to a whole year later. I just found out that girl he went out was a friend of the group. I always assumed it was a random girl not someone he personally knows. He admitted to having a little thing for her. But nothing happen between them. He said she wasn’t interested in him.

So now I’m feeling like the second option. I feel like I was always his second choice. Like this whole year since we got back together things are amazing. I feel so loved but finding this out hurts me because i can’t help but think the what if. What if she was interested in him back then he would never try to get back with me.

Any advice? I made a post about this a day ago but it was a very long post.