I think you will find that one of the few "good" things about all of this is that our relationships, and marriages, aren't as FRAGILE as we think they are. One slip-up doesn't negate all of the things you've done right; simply re-group and start again.
An exception to this would be a wayward spouse's re-contact with OM/OW, which starts the brain chemicals a-workin' all over again, and re-sets the clock to "0:00:00," but everything else is fixable.
I said a quick prayer for your brother, and hope everything goes okay.
