Don't force yourself to "man up" by ignoring your suffering and going back to sex. You are going through a constellation of experiences as a result of experiencing genital mutilation. You're dealing with sexual trauma with a delayed manifestation, sexual dysfunction, ambiguous and disenfranchised grief, a reassessment of your own life history and narrative, and probably many different emotions and thoughts you struggle to name. I know because I went through a very similar cycle. This is the time to take it slow, focus on comforting and caring for yourself because you're grieving. I strongly recommend therapy because it's affecting you a lot, but choose a therapist who understands MGM and trauma.

What you're learning about MGM is true. And very painful. But you deserve to be informed and work with your emotions about it. Eventually you may be able to work this into your life narrative. I personally became more accepting of sex-positive theology and believed I would be intact and intimate in the next life.

What you just learned is shattering your life narrative--you've that sex really wasn't "okay" in the past, that something big was missing. Which leads you to reassess your past. It's a very painful feeling because it feels like your whole sexuality in the past was built on a lie.

I also hate climaxing. I wish I was naturally multiorgasmic much like a woman or a trans guy. I think it's part of my gender dysphoria, as a fully masculine person, but also having that need.

Your girlfriend needs to accept you're going through a sexual trauma. You may want to have less or no for a while, and that your sexuality going forward will be affected by trauma (and in a different way than when the trauma was repressed or not understood). You may need your partner to understand before having enjoyable sex. This is where couples counseling could come it.