Any advice from people who overcame being incapable of self-stimulation?

I've always had a complicated relationship with sex because I struggle with vulnerability (daddy issues, emotional abuse, etc.) but my fiance and I have worked really hard to untangle all that together and I'm in a way better place than when I met him a few years ago. That being said, I feel like this is one hurdle I can't break through no matter how I tackle it.

Background: my attempts have all been made when alone (I want to be able to do this without help), they've all been unsuccessful, I have tried to use instruments, I have tried to use various types of smut. I wasn't raised in a particularly religious or repressive house, I just never felt the need to do that. I was assaulted by a roommate when I was a teenager, but I don't think that's related to this because it never really haunted me or anything. I logically understand that this is a really healthy practice and I don't think it's gross when other people do it. I have no issues coming so long as my partner is involved, so it's not that I don't know what to expect.

Essentially, I've gotten to a point where I can get really close, like 95% and nothing more. And every time I try it makes me unreasonably emotional out of the blue (and I'm not an emotional person).

So I guess I'm looking for advice from anyone that's been in a similar crunch. I'm a girl, but I don't think this is really a gendered thing so anyone is welcome to chime in.

Thanks in advance