Separated after 8 years?

I (F)i was with my partner (FTM) for 8 years and he started testosterone during our relationship. more specifically the last 6ish months of our relationship. I was so excited to be a part of this journey with him. as he explored his gender identity, he realized he wanted to experience intimacy with men to feel affirmed and more connected to who he is. i tried my best to support him and stay open minded because i loved him and wanted him to feel whole but when it came down to the reality of it it was emotionally devastating for me and i realized i couldnt be okay with the idea of sharing him even if it was tied to his gender journey. he ended up breaking up with me because he felt that this was a need for him and not a want. He has said that maybe in the future there's a chance we could try again but he would still need the freedom to explore. I love him deeply and i dont know how to process this or how to respect his needs without abandoning my own. I don't know why it affects me so much but it makes me question everything about me and my worth. I know that's not the case. He's even said he's never wanted to replace me, just explore. but it definitely feels like replacing. Im looking for people who have been in similar situations where a partner’s gender journey and desire to explore conflicted with relationship boundaries; how did you cope? how did you navigate your emotions without resentment or self betrayal, and how do you move forward when love is still there but the relationship needs no longer align? When I say this boy is my soulmate . I mean it.