Then, a few months later, he caught gonorrhea and admitted he’d been cheating on me. why he cheated, he claimed it was that because we’d been having less sex after I’d caught herpes

WHOAH

TOTAL DOUCHEBAG!

It is irrelevant that you were not that interested in monogamy- he should have fessed up the first time- NOT blame you for STDs! You should have walked away after the herpes.