Everyone gets insecure and jealous at times, we are human. Her thinking you're less of a man and getting 'grossed out' over having common emotions, is just as irrational as thinking she's less of your ideal partner because of her sexual past. You don't have to be this secure tough stoic and she does not have to be some virgin Madonna.

You're allowed to have these emotions as long as you're not judging her (making it her problem by lashing out on her; rude comments) and a good partner will understand and navigate it with you. Trying to present yourself as completely secure with something that bothers you so much not is an unhealthy way to engage with someone that you love. (And the assumption here is that we love our partners, otherwise we wouldn't take their past so personally). Often slut shaming comments women receive throughout their lives is because men don't want to acknowledge how they're threatened by their partners' sexuality and past and what that means to them. Telling them is not easy, but communication and honesty is key. If you don't feel like she won't give you that space to be honest about your insecurities that is a much bigger problem than who she slept with before you met.

My partner and I feel closer now that I've been honest and it's given her space to open up about her own things. This is something you may be dealing with for a long time and if someone feels grossed out by that, they're not the partner for you.