I've never been married, but I have loved & lost. Heartache can be very difficult to overcome, but one thing I learned that helped ease the pain was meditation, breathing exercises, & yoga. If there is a local yoga or meditation class they have at your local gym or community, consider looking into it & trying it out. Yoga & meditation are both very self-finding activities that'll calm your mind, soul, & spirit. It may even bring about some inner strength you didn't realize you had.
Keeping a personal journal can help ease a lot of frustration that's in you if you have nowhere else to turn to talk things out. Writing for me has helped a lot get off my chest, & finalize my pain & frustrations into a book that I know holds all of that, but aren't within in me anymore. Writing will also make sense of whatever situations you're going through, as well as help make logic of some areas in your life.
Spend as much time with your children as possible, perhaps enrolling them in some sports, or doing activities with them that will make your bond closer to them. It is probably just as difficult for the children since they might not understand completely, but devoting your time & affection to do something proactive with them will definitely take your & your children's minds off the matter.
I wish you the best of luck! Everything will fall in place, all in due time! Just focus on how wonderful life is; be thankful & have gratitude for all the fortunes you DO have now in your life!