If you just feed from one side, you could express to stop engorgement. I did for one or two feeds when i had a cracked nipple, just hand expressed in the shower. I;m a crap expresser though.

Although BM is still a great source of nutrients for J, he gets nutrients from his food too, so he might get a bit less BM while you feed from one side only, but your supply on that side will soon pick up and the supply on the cracked side will probably drop unless you keep the expressing up.

S now feeds mainly from the L side. My R side doesn't produce much. That's happened b/c i favor the L side. If i feed on the L i can still use my right hand to eat/type/drink or whatever so now the L produces lots more milk.

You certainly have had your fair share of mastitis. I'd feel like crying too.