Sadness

I broke up with someone I was deeply in love with 2 months ago. It was not a clean break, it was not clear. I was being disrespected and betrayed but the reasons why he acted that way were not clear. I'm someone who can let go so much easier when I can understand why. Part of me still wants to be with him. Another part can't deal with his callousness and another part is still trying to understand what happened to my life and my heart. Does anyone have any advice to either work that out and let go or let go without understanding? Thank you.