How do I learn to trust him again?

Basically my other half & I have been through a rough month as he's been having a "relationship" with another woman. Now he's not cheated on me and I don't mean he had an affair but he's been emailing/texting/phoning/seeing an ex-fiancee. It's been going on since June but I only found out about 5/6 weeks ago. To say I was shocked/hurt/betrayed etc is an understatement but he apoligised for keeping it from me and said they were just friends. I wasn't happy about it and due to the deceipt about it for so long wasn't sure I believed him so started snooping. I managed to access his email account which is how I know how much they've been contacting each other. There was some hurtful stuff in the emails but they did seem to confirm it was just a friendship so I just kept an eye on things. Then 3 weeks ago he said he was taking her to lunch for a proper catch up. I didn't want him to go and we had a huge row about it but he said I needed to trust him & I had no right telling him who he could or couldn't be friends with. They had lunch and spent the whole afternoon together and the following week the emails took a turn for the worse and started heading down the path I was dreading. She said saying goodbye to him was so hard & it would get harder each time they met & then she admitted to wanting to kiss him. He admitted to feeling the same and the emails talked about them both feeling sorry for me & C (her husband) but they were the ones that were important and they'd take things slowly until they were sure what was happening between them and what they both wanted. Now obviously he didn't know I was reading his emails but the stress was making me ill & he knew something was wrong. Her final email said they needed to meet to decide how to "do this". I was distraught & couldn't hide it any longer. After an awful weekend with me wondering when he was going to see her I broke down and said I couldn't carry on any longer. He then admitted everything and said he was sorry. He actually told me he loved her & he always had. He said he couldn't help how he felt but he loved me more & wanted to be with me. Now I love him, we've been together 10 years & he's never done anything like this before but now I don't trust him. I never thought in a million years he'd do anything like to me and I thought we were rock solid. I agreed to give us another go but I don't know how to move on. I don't trust him. Whenever we're apart I'm thinking he's contacting/seeing her and when we're together I'm not really myself. Now I know these things take time but my problem is he doesn't actually think he's done anything wrong as there was no actual physical contact and he stopped the affair (before it started) and chose me. He thinks I'm being too hard on him asking where he's going and checking his phone etc and I'm worried I'll never be able to get over this. Has anyone else been through this? How do I learn to trust him again? Can I learn to trust him again if he won't admit to having done anything wrong?

hi, ive been in exactly the same position as you with my hubby and his ex,he emailed her texted,phoned, and met up with her,all to which i found out by her telling me and me snooping my went further he took her away for the night and another time almost had sex but he couldnt go thro with it which i dont believe at all,ive known my hubby for 4yrs and its only in the last few months stopped(i think)but hes ruined everything the trust has gone,im questioning him all the time,and people tell u times a healer but its not it will eat u up inside ,im still not sure wot really happened and never will,i hate him sometimes and things will never b the same again he thinks i should b over it by now and move on and forgive but that will never happen for me anyway,why do some people need to keep in touch with their exes unless children are involved,mine admitted to me that they had had sex and i broke down then he took it back and said they didnt,i think because he saw how upset i was he denied it but my gut instinct tells me they did, whats urs telling u, in my own case i will never trust him again,in ur case i hope you can be more forgiving than me listen to ur heart can you forgive and forget ?if you can your a strong woman , sharon