Oh yes, you have come a long, long way MoreLegs, you should be so proud of yourself for battling through all those hard weeks.
I'm not really sure what I'd do about DS not wanting anything from him for his birthday. If you send him a message that puts you in contact with him which is hard on you, and, judging by the Easter egg fiasco, he's not likely to pay a blind bit of notice.
But in your shoes I wouldn't want DS to be in contact needlessly in case it upsets him. He's obviously angry with his father and I don't see how he can't feel hurt by his behaviour, even if he's never regarded him as the reliable, rock-solid parent.
I think I'd probably say nothing, make sure to intercept the post on DS's birthday and let him know if something's arrived a day or so later so as not to spoil the day for him. Then if he wants he can either keep whatever's turned up or just mark it "return to sender". But that's just what I think I'd do. It's a tricky one and I'm sure there's not a single right answer.
Any sign of snow your way? It's been beautifully sunny here. Perfect for digging up dandelions, ivy, ground elder and bindweed while supervised by mildly curious cats - their company is their contribution to the work.
Sleep well.