Yes, went in a full on depression: lost 8 kg (1 stone and 3 lbs), couldn't sleep anymore, started rethinking what I had done and what I could do. As sad as this may sound I even had very very brief suicidal thoughts about which I am definitely not proud of or happy about, but managed it rather easily. (I developed a positive thinking system to pull myself out of those situation).
I slowly picked myself back up, by focusing on muscle preserving foods, in order to use to my advantage my lack of hunger.
When I started feeling a little better, restarted working out, trying to be social although it was hard.
I avoided drugs, alcohol. Because that could really push you to do stupid things.
As of right now, I am considering the rebound option.
Result, I today am getting much closer to the 6 pack goal I have lost hope for. I still feel sad when I am alone because it gives me time to think about what I had lost, but it is bearable. I had my heart broken twice, The first time it happened, my personality got much stronger and made me who I am now, the second (latest) was tougher to handle (4 amazing years and a stupid reason), but if you just give time some time, it will take care of it. promise.
Try to ignore it if you can, or keep busy, alcohol is still OK but only when you are with friends and in a happy mood, not when you are sad and desperate because it reinforces your current emotional state.
If necessary you can go get some rebound but try to enjoy it too, don't do it as a job lol.
I hope it helps.
Note: There will be someone else even if it is not the right one, when you will meet you will start feeling better. I last week met a nice girl and we just hit it off and kissed, for the moment I was with her I didn't think a second about my ex. So keep positive, and look out for your next conquest ^^.