Well, you did a good job of being inaccessible there, but you may have been able to diffuse much of what you endured had you simply called him back when he got home to explain the homework situation. Not that it may have made much difference, no matter what you do, its never good enough these days. Notice how he referenced the OM during one of his tirades?, who knows, he could be a little jealous..
I wouldn't change anything, if he blows up at you, just stay calm, listen, and DO NOT DEFEND YOURSELF. Let him steam himself out until he knows that no matter how much he huffs and puffs, you're not going to let it get to to you. Then, always thank him for calling, tell him you've got to run, and thats that. Then, you stick to the basics: act calm and confident, don't initiate calls outside of issues with the kids, act happy just the way things are, no PRESSURE, and continue to do your own thing.
If you want to call and wish him a happy BDay, fine, keep it upbeat, but I'd probably stick with having your kids call and wish him a Happy Bday and leave it at that..
