Struggle with co-existing with an ex

we share children and are around each other a lot. even though I know we cant work it out, its hard for me not to stir up emotions. sad ones, angry ones, hopeful ones. I wish I could turn it all off. im only hurting myself. I want to be able to have a normal "relationship" with him but I feel like its so hard right now. to see him make the choices he does everyday. I need to understand he is going to be the person he is going to be. that has nothing to do with me....but it hurts.