New to being in a relationship

I met someone that I’m so in love with. We both have same morals and everything else I’d want in a relationship with a man.

I have never dated anyone (I have been on dates, never hooked up with any) my past is short

He is the opposite (has much experience sexually before he knew God, and has two exs)

I’ve come to accept that and I truly don’t judge him for anything in his past cause I see change in him. EXEPT his one ex.

I’m having really bad what I think is insecurity issues. I’m thinking back to his first ex that ended on good terms and still follows and likes his social media posts, she’s beautiful, 4 years older than me and that was a year ago they broke up.

He gives me no reason to not trust him, but it’s the feeling that hes not completely in love with me, or she has more of a hold on him then I do. Or why does an ex still follow and like your things if theirs no attractive?

He’s open about me and doesn’t hide me.

But I’m always fighting these horrid thoughts of I’m not good enough or I’m the “found someone to settle down with cause the ONE got away”

I’ve prayed about it, I’ve begged to have these thoughts lifted away, I’ve asked for peace knowing this is not from god, it’s extreme fear of heartbreak.

Being cheated on or being in a relationship where the partner cheats secretly scares me so much like it would anyone else.

Does anyone know how I can wiggle past this? What I can pray about, how to love him without fears on my chest?

I’ve mentioned to him my fears, he understands but reasonably it can frustrate him because he hasn’t done anything to lose any sort of trust, he reminds me it’s fears and that he loves me and only me.

I’m just scared this one woman will cause a heartbreak in my relationship that I feel is destined to be for life. I’m so in love and so bad at this whole relationship confidence thing.