Having to take plan B! Don't judge me

I was trying to Conceive with my ex boyfriend and we had sex on Wednesday and I just found out something that hurt me and I slept with someone and he came inside me I don't want to have a child with this guy and glow says I'm fertile if I take a plan be will it possible terminate my pregnancy with ex he texted me this morning and said he wants to fix everything and have a child still so should I take the pill tomorrow that passes the three days with my boyfriend and it will be my second day with this guy someone help me and don't judge me please