Help 😞 who do i choose my ex or this guy ..

My fiance of 4 years cheated on me .. I found him chatting with his ex gf on snapchat he was talking to her bettter than how he talks to me ,im not gonna lie it hurt sooo bad . we still live in the same place together i broke up with him cuz i was not gonna tolerate a cheater . i ended up meeting a guy on tinder he is so sweeet!! And doesnt care that ibhave a son he wants to give me a great future , BUT im not ready to move on my EX Is constantly telling me that hes gonna change and that he needs me and he fucked up... What should i do??? Who should i choose im so confused i can barely type