advice!!!

i finally got over my ex that i was with for like 6 months n started dating this other guy and my ex saw it and got jealous, so he came to my work to see me and was telling me to dump the guy im with for him...i guess what im trying to say is the guy im with now has lied to me and he has been caught in lies n my ex hasnt lied or anything.. idk which to choose my ex or the guy im with now help!!!!