In the beginning, I didn't want to ask. I thought that made me less of a mother somehow, or I should do it all since DH works.

But after a few weeks of colic, that all changed. I felt like I was about to lose my mind when DH got home, and that break was the best thing in the world for me and DS (who would often calm down temporarily with DH, probably because he wasn't frazzled yet).

You need to ask for a break, even if it's 15 or 20 minutes on your own. Or ask DH to give DC a bath or put DC to bed. It's good fro DC also, to get used to having both parents do things for them.