Wow. What you said....everything you said.....I can completely relate to it all. I mean, I'm constantly amazed at how I can come here and find other people who are going through the same things as I am; it makes me feel like more "normal" (I hate that word too btw!).
Well, it seems like all you have is your boyfriend. I'd have a heart to heart with him, as best as I could. I'm really good at writing letters and then reading them aloud, so I don't lose my focus and this way, he has a tangible copy to read over again. I'd tell him what I was afraid of (losing his love and acceptance, him thinking I was off my rocker for real, him not helping me, etc), all of my personal insight to my problems/issues that I have (like what you expressed in your posts) and how hard it is to ask for help on top of all of that. I'd reassure him that it's not his fault, that he did nothing wrong, that it's not a relationship issue but a rather a personal one, and that it's not up to him to "fix" me. I'd remind him that no matter what, I still love him and no amount of therapy will hurt that; in fact, if therapy helps me to be a better version of myself, then it's really opening me up to giving and receiving MORE love. I'd finally tell him that I am going to find a way to get the therapy I need with or without him BUT!!! it would be so helpful to me if he was there to support me. Tell him you WANT and NEED him and his support, but that the option of not getting therapy is really not an option at all. I would dig my heals in and not take "no" for an answer. This realistically, may take more than one conversation to get him to understand. That's OK. Better late than never; some people need some time to "digest" this.
You know, men by default LOVE to help and actively need to DO something for us and our problems to feel useful. This in turn, tells him that you love him when you accept his help. Tell him that his driving you to therapy and supporting you by keeping an open mind, not being judgmental about your treatment, and giving you lots of non-sexual hugs is the best "help" he can give.
Good luck with telling him; please repost with an update if you can/want to. I hope he is understanding and that you are able to get to therapy.