OK so let me try to help... listen, if you had to "cheat" on your subutex program you sure picked a bad drug to do it with. The easiest transition is from short-acting opiates to subutex and methadone is the longest lasting opiate in the world.
I know this advice is a bit late but I'll explain it in case somebody else reads this thread one day who needs to know....
If I was in your situation my strategy would be like this:
Get off of the methadone and then go as long as possible, delve deep into the pain of withdrawals, at least two days. It won't be fun.
Then take subutex and expect the withdrawals to get even worse.
Then take more subutex. Then more. Then more still. Then some more. Pretty soon it won't make you feel worse, it will make you feel better.
While it will be unpleasant it will still be better than the alternatives of (1) fully going through methadone withdrawal, or (2) feeling precipitated withdrawals in full force.