Idk what to do

Yesterday my best friend asked be out I said yes because I can’t hurt him. I thought I felt the same way but today I found out my ex that I think I’m still in love with is like really jealous, he went up to my cousin and said “what the fuck” she then said “what” he replied “Alexis and Jake are dating why didn’t you tell me” she then said “ it’s none of your business” he said “She was supposed to love me and only me” idk what happened after that but idk what to do can someone please help me