You said you hadn't told your boyfriend, but have you told your family about your depression?
If you feel that way about your ex and you think he's a decent enough guy to listen to you then maybe tell him? If he were to be back in your life as a friend who can support you would you be happy with that or want more?
If you haven't told your family then I think that'd be the best place to start. Only do what you're comfortable with and in your own time, but your family will be able to support you better if they understand why you are behaving a certain way.

wishing you luck,
molly