heart broken

my boyfriend decided to move out. we been dating for 4yrs now, friends for 11yrs. we we're trying to have a baby. even talked of getting married. we argue about things. but this week, he seemed not him self. he wasnt talking much to me or having sex. i finally asked is everything ok. he said " no, theres lot going through my mind. i love you but i cant be here." of course i blew up and said just leave now. wasting my time and my sons. then of course i started crying, asking why. i can tell he was sad. but he didnt say sorry. just said ill be here tomorrow pick my stuff up. im heart broken, confused. i dont even know. i dont have much friends so i came on to vent. i rather be cheated on then this. i dont know what the hell i did or what made him change is mind about us.