Ask him.
He obviously loves you deeply.

He has stuck with you knowing what you deal with, at least the result of dealing with it.
Whatever he sees in you is such that seeing the pain of a loved one and feeling the pain of seeing that is worth it.

I once had someone very close to me.
I opened up and she didn't ridicule or shun me for cutting myself.
She was sad and angry that I did it but she accepted it.
Eventually, I saw just how much deeper my cutting cut her than it did me.
I held that thought close to my heart whenever I felt the urge...

Just remember.
You have the unconditioned love of another.
You have life in spite of your pain.
You have empathy as per this post.
You also have the blade...

So please.
Find your sheath, because when you cut yourself.
You cut those you hold closest.