@stomachcramps
You have SO got this! I can actually hear your steely resolve in your typed words.
I think the first things to do would be to see a solicitor and (if you feel the need) source counseling or therapy for your DS in case he needs the extra support. You don't necessarily need to sign him up, but having the ready resource might make it faster if he does need extra support. And remember that you have made him feel loved and secure, you've given him a good foundation and a rock to lean against. He may well surprise you.
I think a solicitor is important because you are the higher earner and you own a house. You want to be sure that you come out of this in the best financial position, including buying him out of the house if that becomes necessary. I think (but am not sure) that even if you owned the house prior to the marriage, there's something in the law about 'the marital home' that may muddy the waters. You also want to be sure he can't frame himself as DS's 'primary caretaker'.
I agree with a PP that I'd pack his shit up, deliver it to his parents, and tell him not to come back. I realize that those 'muddy waters' I mentioned above may include whether or not you can legally kick him out of the house, but if his 'tik tock totty' lives near his parents he may well decide to stay there. It has the added advantage of being sure that his parents know the real reason for the split. If he decides he's going nowhere and comes back to the house, then blank him. Do not provide any 'services'; no cooking, laundry, cleaning up, life admin, and no financial 'assistance' if you've been in the habit of covering any of his expenses. Buy and store separate food and let him know he is not to touch it. Let him know that since he wants to have 'the bachelor life', then it starts now.
Harness that fire in your belly. Stand tall.