How do I deal with jealousy in my first ever relationship?

I need your advice. I (21F) met my gf (23F) six months ago. She friendzoned me in the beginning, we were friends for a couple of months. Because of this, she told me “lore” about her exes, and said she cheated a few times before.
Later we started hooking up and after a while she asked me to be her gf. I refused a couple of times and expressed that I do not feel secure in her (because of her previous history, our rough start, and her general unreliability). Yet we continued to see each-other everyday, she told me she loved me, and we were exclusive. Some time later she said someone she matched with on tinder months ago just texted. She asked “how do I say I don’t have a girlfriend but things have changed”. I remember thinking to myself why wouldn’t she just say no. Later that day I said “maybe you should still meet up for a friendly beer” cause they had a lot in common. She replied “yeah, we agreed to”. That took me aback cause if I didn’t say that she wouldn’t tell me. The next day she tells me she’s going for a beer. I automatically assume it’s with the tinder girl. I try not to express jealousy because we weren’t dating at this point. I meet up with my friends and feel terrible anxiety the whole day. I decide to send her a voice memo sharing that I don’t understand why she’s still looking for other people, I thought she wanted me, and I told her I have an issue with trust, why is she doing the one thing that stops me from entering a relationship with her. Here’s the twist: she tells me she doesn’t know why I assumed she was going on a tinder date. She was actually seeing her ex fling from another city who’s in town for a few days. I was heartbroken. She says she didn’t lie, she just didn’t explain who she’s meeting, not wanting to upset me. She says her conscience is clear, it was a friendly meet up. This really triggered my anxiety cause why did she lie, she wouldn’t have told me if I didn’t confront her because of a gut feeling. We meet up the next day, she apologises – I don’t accept her apology but we continue as normal. Next day she tells me she wants to see her again, asks if I’m okay with it, she won’t go if I say so. I don’t tell her no, cause it’s her decision to make. I keep crying about this for a week and I finally bring it up. She was understanding about my feelings, told me all about their fling so I understand the situation. I felt a lot better, I trusted they didn’t hook up or anything. We started dating and everything is truly great. But I can’t seem to get my mind of this. I still feel betrayed and lied to. She’s had a lot of exes, I have none, I don’t know what a friendship with an ex is like. When we are apart, I feel like I’m not special and am just filling a function. I don’t trust she won’t cheat on me. And I sure don’t trust she’s over her exes.

Help, I have no idea how to deal with these feelings, I want to move on. Should I bring it up, is there any point in that? How do I bring it up so she doesn’t view it as an attack?

TL;DR; :gf lied about meeting up with an ex, explained herself but I still feel betrayed and lied to