How to get past betrayal from my husband?

my husband cheated on me 7 weeks after our son was born i knew from the day it started but didnt have the proof to ask him for a month when i did it took me 2 days to get most of the truth from him, he said he thought i was going to leave him as i was being distant but i was only 7 weeks out of giving birth by c section and my son was also very ill at the time aswell. all it took for the girl to get her claws into him was her flashing her he not only risked loosing me and our children but also his job as they both work for the same company as security guards, he was only physical with her for one day from what i have been told but he spent the month texting and calling her. i have decided to stay with him as i love him to much to walk away at this moment in time but i am finding it extremly hard to get past it and to trust him when he is working even though he is on a site by himself as he was for the month he was in contact with her.