Trying to conceive.... and this happens....?

What do i do??? Me and my fiance' are trying to conceive... just had a miscarriage 7 weeks ago.... and now last now something just told me to check his cell.... (gotta love a womans intuition) there was a text in the "drafts" that said "just thought i'd offer sweetcheeks, hollaback" i confronted him and he said it was his ex. I told him i was leaving.... packed what i could up and tried to leave.... he wouldnt let me. He doesnt want it to be over... I have 2 kids from a previous relationship... and he works 60 hrs a week just to put a roof over our heads, i feel like if he wanted her he wouldnt be bustin his *** and rasing kids that arent even his. Please help!! Tell me your opinion please!!