Argument gone too far?

So my partner of 2 years thinks it’s okay to tell me he’s slept with other women behind my back and I quote ‘they love it’ every time we have an argument.. he says it literally all the time!! And then back tracks and swears on his children’s life’s (he has 3 from a previous relationship) that he said it to annoy me and hurt me? I’m sorry but I find this beyond a joke now and quite frankly disgusting!! I’ve been cheated on in the past and this actually really effects me.. my last partner cheated on me and give me an sti resulting in me having an ectopic pregnancy and loosing my Fallopian tube, So I get extremely anxious about all this! It’s not fair! Think it’s time to just leave now.. how can someone be that hurtful and say things like that to another person!! 😔