The Bachelorette in real life

So i've had this ex that i've been on and off w and we were off one week and this guy dm'd me on twitter so i've been talking to him for almost 3 weeks now and now my ex is telling me he loves me and wants me back and idk if i should go for the guy on Twitter who is amazing or my ex who we dated for 2 years. I really don't know what to do about the situation and I have to tell one of them no.