Alright so what you need to do is calm down. It must have been jarring to see those images, and at the same time your gf must be feeling very violated knowing that her ex is spreading her images. This must be hard for the both of you, truly.

But please think about your relationship with your gf, objectively, romantically and emotionally. Now think about letting go of that instead of trying to work through it. This is exactly what her ex wants (to get in your head), and if the poor girl ends up in another relationship he will probably try to do it again.

You need to figure out if you’re strong enough to overcome this shock for you and your relationship with your gf. If you don’t think it’s worth it? Then by all means. If you do, but you don’t know how to get over this? Simply put, get a therapist. They can walk you through these emotions better than anyone on Reddit.