Am I over-stepping asking her to delete EX guys shes fucked on facebook? (Should have changed the title)

I'm 25, barely getting into nursing school, and really wont have a career set for another 2 years at best. My GF is 30, she has a PhD and is from another country studying as an international student. We've been together for 6 months now and she's treated me great. She's done more than I have asked for and in fact, post-poned her graduation in order to stay with me while I finish school. She really talks a lot about marriage, which I'm not entirely against.

One week ago, she mentioned that she's slept with 3 different guys, all LTRs (1 to 3 years). She's mentioned exes in the past, and I was able to put 2 and 2 together and determine some of these guys. It turns out they all pretty much used her took advantage then kicked her to the curb when she was done being their cum-rag and started asking to take things the next step forward. So im not the first she's considered marriage with.

One of these guys was one of her first friends when she came to the US, and they adjusted together and learned english together and went to college the first 5 years together - so they share that bond. They also share the bond of her swallowing his cum, so I explicitly told her that if she is in contact with him, or any of them, I will leave her on the spot. So much that I dont want her even telling them happy birthday. If they message her, I want to see the message, and want to know why she felt inclined to reply to them. I told her "I would prefer that you delete them off social media, I dont want them seeing who I am or that we're together, I dont want them knowing my name or what I look like, etc..." I told her she can keep any other friend or ex, but if she's sucked their dick and they've nutted in her, for her to think of them as nonexistent.

Seeing that Im not exactly in a spot to make demands like that I'm taking a step back because this might be retroactive jealousy. On the other hand, I cant have sex with her anymore. She's a starfish (and is working on fixing that), but I cant help but imagine that she was probably not a starfish with these guys and was a lot more into it.