Eating healthy and exercising really help me. I dropped 14 pounds in 3 weeks when we first split. Couldn't eat. Yogurt helped me to keep something in my stomach and not get sick.
Honestly, I was too depressed to do much cardio work, but I found that walking in the neighborhood and getting fresh air helped quite a bit. Yoga was also a godsend. It streches you, you move at your own pace and the breathing really works to relax you.
Right now I would suggest a routine and just do the routine as scheduled. Going through the motions at least keeps you moving and on a schedule.
I isolated too much and I would recommend not doing that.