You haven't mentioned your feelings for her. I see then no source for confliction other than your need to be a closer parent to your children (3 times a week is excellent - is this visiting or co-parenting?). What I believe really needs to happen is closure - especially as your wife is having difficulties realizing the current situation. It's been 6 years. Perhaps it is time to cut that final apron string.

BTW I think it great you are as involved as you are. Many children with both parents in the home don't get that kind of time with a parent. I applaud you!