Jim, I know EXACTLY how you feel. Even though the OM has since been out of the picture for me. The fact that my W has said she wants to "see others" makes me sick. When these thoughts enter my head, I sulk in my depression, feeling sorry for myself.
I am constantly worried about what she is doing, where she is at an such. It's not healthy, but it's a struggle we all have to deal with. Until we can ignore the fact that we love our S's to no end, it's near impossible.
I use most of my time doing things arounf the house and with the kids. When she is home all I want to do is be around her, so I try to find something to do outside the house; gym, run, visit family, just walk aroudn a store or something.
ME: 29 / W: 29 M: 10 (11 in March 2015) BD (ILYBNILWY): 07/26/14 S:12 / S: 7 "We need to separate" : 08/31/14 Wants to see others: 10/11/14 Separation looming