How to get over girlfriend’s past sexual partners?

After learning of my 28M girlfriend’s 33F previous sex partners, I’m struggling with intrusive thoughts imagining her sharing that intimacy with them.

I know it’s irrational and rooted in jealousy/insecurity, and I’m typically not a jealous or insecure person, but for whatever reason this is really getting to me.

She has only had 6 partners, so it’s not like she slept around a lot, but I’m still struggling to get over the fact that 6 other men have shared in the same level of intimacy that I’ve been experiencing with her the last four years we’ve been together.

How do I accept that she can’t unsuck their dicks? Someone help me get the fuck over this please.