I’m [24F] afraid I’m (self) sabotaging my relationship by trying to ‘catch my partner [26M]’ doing something wrong, and I hate it

Long story short, I’m \[24F\] in a medium distance relationship (for about 5 months) with some emotional trauma from my last relationship (used to get emotionally abused to a certain degree, silent treatments, severe lack of proper communication) and so far my new partner \[26M\] (of 4 months) has shown me a lot of love and kindness. He is very understanding. I still remain so scared to lose him, scared that he will cheat on me, hurt me, flirt with others… He has flirted with 2 girls (by making a flirty joke that went too far imo) when we were together for a few weeks (and recently again) and he has apologized multiple times for taking it too far, and I feel like that has set me back A LOT in our relationship, even though I really didn’t want it to.

I have been advised to go to relationship therapy but that will cost me €100,- per 60min session and I am a broke student who’s barely getting by as it is. I simply can’t afford it.

Please, any tips and suggestions are beyond welcome. I notice I feel anxious on the daily about this, even though I visit a different therapist (covered by my health insurance) every 2 weeks. I am also taking a study trip next week and I won’t be able to talk to him much and the thought that keeps crossing my mind is that I’m afraid he’ll flirt with other girls, and I just want to stop being so damn anxious and just let things play out instead of trying to foresee every possible thing that could (but probably, hopefully, won’t) happen. Due to my past relationship I also have some trust issues, so reassurance sometimes just doesn’t do a lot for me, and there’s nothing else he can do to reassure me either 🙁

TLDR; I’m very anxious in my relationship and I don’t know how to fix it :(. Do you have any tips?