Did he cheat on me? not intimacy?

my boyfriend recently left our house and told me he went to stop at him mums. while on the way there he didnt text me or speak to me even though it takes well over an hour then he did for 10mins then didnt again for about half an hr then did for about half an hr then didnt for another hr. hes not really secretive or anything like that does hide his phone or go out randomly apart from this week. i dont care about the to be honest i just cnt stop picturing someone runnin their fingers through his chest hair n him touchin them or them kissing it makes me physically sick. we have a 2 year old daughter and a baby on the way. since then he keeps threatening to walk out again. we dont have fun anymore and i no its hard but when i try to make things right he doesnt seem to respond at all it seems like he doesnt care i told him he walked out he wouldnt come back and i let him back. i love him more than anything and dont see why we cant be happy. i used to self harm as a young teen and last night i did it again due to all this building up can anyone help me please? x