I'm sorry to hear this. Trust me, you're not the only one that's lost a relationship upon revealing the ABDL side. I lost a couple of relationships practically the instant the diapers were revealed.
It hurts. I've always been of the mind that I should reveal early on, but even then it still hurts. When it feels like something's brewing, then suddenly it's done, that's not cool.
But, I think there's some good in it, too. I maintain that in order for a relationship to be a viable, workable, sustainable thing, partners have to accept the particularly deep-seated and odd quirks their potential mate presents. I think it disastrous for a relationship if something integral to one partner's being is not accepted or, worse, is actively disliked or mocked by the other. And I feel ABDL desires fall into that realm. I mean, if the relationship is meant to last long-term, but you have to hide, bury, or otherwise get rid of something you feel is a core part of your being, then that relationship is doomed. At some point, you'll come to resent your partner because you want to wear diapers or do whatever thing, but they're holding you back.
And that's no way to have a relationship.
So, I empathize. I know how it feels, and it sucks. It sucks that when you start to feel a connection, that it's quashed. But, I maintain it's ultimately for the better. If they can't accept key aspects of you, then they can't accept you and they're not the right mate for you.
Chin up. I know it hurts now, but better this and now than spending years or more with someone that doesn't accept you for you.