Try to take some deep breaths and slow down. You're only human so it's understandable that after the few weeks you've had you finally reached a breaking point. But backing off and cooling down right now would be best for YOU.
A question I had for you about your conversation with your H this weekend is WHY does he want you to file? Is there something else going on? Does OW know the whole story or has he told her that you want out of the marriage equally???
Oh and by the way you are NOT a f'ing loser for wanting to stay married to your H and the father of your children. If he cannot see the strength that takes, then HE is the f'ing loser.
Can you go work out or go for a run???
But what is happiness except the simple harmony between a man and the life he leads? ~Albert Camus