As for time it's hard to say, you two are young (I'm 28 btw) sounds like your wife thinks the grass is greener on the other side. IMHO go as dark as you feasibly can, if she calls you to "vent" or for support, just tell her that it is not fair to you for her to come to YOU when she broke your heart, not the other way around.
The time will just depend on how stubborn she is. She may never come back. She may rather live in squalor with a dead beat than acknowledge she was wrong.