2moro, Put your focus on increasing the connection in your M. Think of the OW as a weed that can't grow if the lawn is healthy. The power is on your side.
How is the connection in your M?
If he's been home for three months, you have something to work with. I agree that an ultimatum is premature. Ultimatums unless well planned are more about impatience.
CL
CL 53 W 54 M 20 yrs. 03'-09' Separation + Old Patterns + GAL 10-14' Piecing
"The Master allows things to happen. She shapes events as they come."