boyfriend cheated on me?

last week i found out my boyfriend of a year had been cheating on me for 6 months with another girl. in september him and i took a little break but we still continued to talk the entire time. me and him started officially dating again september 19th but he’d gotten into a new relationship september 11th. the girl he’d had an affair with found out about me so she threatened to tell me. i guess he got scared and told me first. he told me everything and started begging me not to leave him. he said he only had real feelings for the girl in the beginning and after that he just didn’t know how to break up with her. he begged three days straight until i finally gave in. i decided to give him another chance because i do love him and he seemed genuinely sorry. the problem is i’m still really really hurt and i have feelings of anger towards him. him cheating on me is all i can think about when we talk. he says he needs me and can’t go a day without me and that he’s cut the other girl off completely. should i leave him completely? or wait for these feelings to go away?