My heads telling me to leave but my heart wants to stay.

So my fiance has been acting different lately. Hes been alot more defensive and lying about having a phone ( he broke his last one). Ive felt it twice, he told me it was a stack of cards. Then once i heard him taking it off the charger then he farted immediately after trying to cover the sound. then a couple hours later i heard the phone dying. He was like i dont know what your talking about, and threatened to leave me. Then last night he was in the room i seen something black and shiny by his head and he immediately jumped up trying to hide it. And he was trying to convince me it was a deordorant behind his head. And hes been leaving every friday. Im torn i want to leave because i know hes lying to me but i want to stay for our 3 month old son. I just dont know what to do i feel like im going crazy.