Jealousy is killer

TL;DR: I have abandonment and trust issues and I need help coping with them for my relationship. The anxiety is killing me and I feel like I want to die because of it

I (25F) am in a relationship with a wonderful man (27M). We are currently in a long distance relationship. I’ve been struggling with dealing with my jealousy when it comes to my boyfriend talking to other girls. He deserves to talk to the people he wants to talk to. When it comes to his ex, I’m not insecure about it but typically it’s when he meets and talks to new people, it bothers me a lot. He’s not at fault. I trust that he will never abandon or cheat on me because I believe him and he’s proven himself. I really love him and I can’t deal with me asking him a lot of questions because I don’t want to interrogate him nor do I want to insinuate anything. He’ll gladly answer them honestly because he really cares about me but I feel so shitty because I’m always overthinking that he always had to explain himself to appease my needs. It’s really unfair to him. Even with white lies (or I assume), they trigger me so much. As for me, I talk to more people than him. I talk to both guys and girls and it doesn’t bother him if guys approach me because he trusts me that I will do the right thing. But i don’t know why it’s so hard on my end even if I know I trust him, I struggle to deal with my thoughts that I would be hurt in any way.

In this, I’ve been going through therapy and I’ve been trying to do more things to pass my time because I don’t want to push him away because of my constant need of reassurance. My ex cheated on me multiple times, my therapist told me that my issues are not only from my ex but also deep rooted which includes my issues when my family and people who I thought as friends have abandoned and betrayed me including the inconsistent treatment I had. I was told that I had an anxious attachment style. My therapist told me that he’s not the only one that I’m like this but with everyone that I meet in general. I acknowledge that he’s not the same as my ex, my family nor the people who have hurt me and I really wanna be better but I’m not sure how I can be stronger in this. THIS IS KILLING ME AND I REALLY NEED HELP. It feels like I'm dying because of how much pain I feel even if it's all in my head

Can anyone help if you’ve experience this sort of thing with your partner, how do you make it easier in accepting the facts and not the lies the brain feeds?