Heartache vs depression?

This sounds like a really tough situation. It's something that could easily lead to depression for you. I think you're right about cutting contact and if you haven't already done so you should cut the contact. When you have a lot of free time you tend to dwell on bad things that have happened to you. I think you need to break your routine and take up hobbies and pastimes that will involve you meeting new people and give you less time to dwell on what has happened. If you're still finding this to be a problem then perhaps you do need to talk to someone professionally to help you work through your situation. Best of luck to you.