How can my 26 year old daughter get over a breakup with her boyfriend of three years?

It seems that you need to let your 26 year old, grown daughter handle the ending of HER relationship in her own way. You haven't mentioned that she's suicidal, self harming or depressed. Step back and get out of her business. She'll cry on your shoulder if and when she needs to. SOunds like you and your family are stalking this guy....you seem to know way, way too much about his business since the break up. It wasn't your relationship, you weren't vested in it since they weren't married, or engaged....let it go. She will move on as soon as she needs to...let her cry and be sad for a little while.....