Until someone with a lot more experience chimes in, I'll just keep reminding you that you don't need to DO *anything* ***right now***. Because anything you do will be reactive.
Just like in your post up there ^^^, where you promised yourself if you felt overwhelmed you would take some time to cool off and process, I think you owe that to yourself right now.
I'm trying to find out your H's reaction to you blowing up to help you figure out how to do a little damage-control in that area specifically.
Can you tell us more about how he seems to be handling the news about OW's move? And tell us more about your latest communication with him. I don't think anyone's gonna beat up on you over you losing your cool this time. This is devastating to you, I know. But remember: OW is moving closer to your H. He isn't moving closer to HER.
I know that doesn't help your wound right now. But just know that your H may have had nothing to do with this. Let's give him the benefit of the doubt for now.
M: 40 H: 44 Married 14 years S11 & D6; D20 & D19 from previous M 2BDs/PAs, 8 years apart Piecing: April 2014