Time. Replacing it with someone else is not good. Time heals best. If you must substitute, get something inanimate like a useful hobby (creation out of destruction) or a pet that will love you unconditionally back (trust and responsibility for someone/thing else).

Mind you, a cardiac surgeon might be useful - it depends just how broken it is. If you still get palpitations or dizzy spells after a year, get it checked out!

LTS