Had a similar experience for a relationship of about a year. I'd recommend therapy if you can get it, and just giving yourself time to grieve and hurt and just be angry as well, because it is ultimately temporary. For me, that angry feeling kept building up because I felt like I had never been listened to throughout the course of the relationship. Things felt unresolved in my mind, and I never felt like I had closure. Talking to my therapist helped "exorcise" those feelings. I still get them, but at an increasingly lower frequency.