Boyfriend trouble

Ok so me and my boyfriend have know each other for 13 yrs we tried dated in the past but we didnt want the same thing know that we both have matured we started dated weve been dated for 3 months now almost 4 months and were also 11 wks pregnant and i just found out for the past couple weeks he has been sending and receiving naked pictures there is email he has said that hes never acted on them just sent them and received them he wasnt talking to them just send pics back and forth it upset me every much were starting a family know its likr how am i supposed to trust this man again he promised that he wouldn't do it again and i did agree to give him the chance but i just dont know how to push past this i keep trying to go threw his phone and im scared when he says hes at work hes really out cheating what do u think i should do help me? Do i make him gain his trust? Do i just never trust him again and make him walk on egg shells? I dont wanna push him away i want to try and make this work ive always had a crush on him and i do know he has cheated in the past and ive always believe once a cheater always a cheater but i have talked to his ex wife and she said that he was faithful during there 4yr relationship she actually cheated on him ugh what to do please give me ur advice