I agree, at 5 months he is almost ready for weaning, it's not mentally healthy for you to be so attached toeach other. And all of the (very good) suggestions for getting some time away don't work when you're so attched. It is possible to change this if you really want to. After all, when you've got 1 more dc it's just not possible to devote so much time to 1 baby,
I agree, he's being very selfish, and I would be furious and fed up too. But if you can stand to look at it from his pov, you're attached 24/7 to baby, he's lost his place with you, he probably feels all you ever do is moan/scream at him, so he stays away even more, you get more angry and frustrated and cross with him, he stays away even more.......
From hard experience, I've learnt if you want to make something to happen, you need to ensure it does, not wait on someone else, cos as you're finding, then it just doesn't happen. Plus, the more attched to ds you are, the more resentful, jealous and lacking in confidence your dh will be.
You need to get to the point that you can leave your ds. Even if bf, at 5 months he can be left for a couple of hours. during day. Why not, at weekend, feed ds then tell your dh you need to go out and leave them together? Then have a good couple fo hours, NOT grocery shopping. Get a book, go to a cafe, go shopping for a treat, get your hair cut. YOu need to look after yourself. And no matter how much you want your dh to look after you, you've said yourself, it's not happening. Ime, men need telling in a matter of fact way what you expect, rather than moaning at them.
And I'm sorry if it sounds mean to you, really I mean the opposite. I spent a long time being a doormat to my dh and 3 sons. But in the last year have only just come to this realisation (doh, took me a while), and try to have a day off every now and then (dh's face when he was left with 3 kids for the first time, ha ha ha). YOu will be empowered if you start doiing it, rather than getting cross with him for not doing it. And he will maybe not like the extra work on one level, but he will like having more involvement with his ds, finding his wife a bit happier, and more assertive.
Good luck.