Agree so much with comments here!
I think you need to work out what works best for you. I mean if you've been in a 20 year marriage and it's ended - it's a different process to if you've been dating for 3 to 4 months. Not a different heartbreak necessarily - but a different process.
There is a saying that pain is mandatory - suffering is optional.
You have to go through the pain to get the closure- but after that you can choose not to feel the ongoing pain that we usually feel after the breakup (ie: the suffering)
So keeping to this - I have used self hypnosis in the past quite effectively - and if you can't do this yourself sometimes you can just find a hypnotherapist who will help - they just start to work on the thoughts you're running through your mind that are allowing you to feel broken hearted.
I'm not sure if it's your thing or too way out there, but if you look at how calm people get when they meditate, you can see the affect it has.
Also - so important to keep healthy through it too - I remember once I was juicing and exercising a lot and the happy feelings you get when you're at optimal health overcome the depression you feel.
Anyway, hope that helps - sorry if it's too way out there!