Mate, I know how you feel. These times are like being on a rollercoaster and you feelings, emotions, finances.....it's all going up and down all over the place. Just remember one thing though.....Your kids love you and you love them. Be strong for them.
Life can get real shitty but there will be a turning point when it starts to turn your way and brighter days arrive. It may not be today, or next week, but it will come and your kids will thankyou for being strong for them.
Try and do something to help you get by, a new hobby, join a club, or meet someone for a game of bowling. Apparently axe throwing is the new craze at the moment.....imagine it is your Ex. Whatever you are into. Something to take your mind off things.