Partner asks an older woman for sex/touching

So i am looking for a little advice /support please. This is gonna be a little long so apologies but also if you read it thank you.

A little backstory first - Last saturday my partner was at work and normally i give him a lift to and from work as he doesnt drive. Normally if he finishes at 9pm his mam gives him a lift home as i like to have the kids in bed by 8pm but this week she was away. I said i didnt mind as it was a one off but he was adamant he would get a lift home from someone, even though i kept saying i didnt mind. Thats was kind of the first clue something was going on. The next which made my gut feelings really go off that something wasnt right was he text later saying he had been offered a lift but i just had a horrible sinking feeling reading it. He came home around about on time, i think as i had been asleep. I had put it out my head and put it down to past trauma with my ex who was somewhat seeing someone he worked with behind my back just after i had our son.

So fast forward to sunday afternoon and for some reason i go looking through his messenger and find messages to the woman who gave him a lift home, a very much older woman (im 32) where HE had asked for the lift and that he wanted to experience a mature woman. She had said no, she was flattered but not looking for any relationship. He goes on to say he wishes she had tried to touch him up and that it would be friends with benefits or something like that, no feelings involved and if she could put the feelers out to someone else he could get with but to keep it quiet as he didnt want his name involved. I was and still am absolutely devestated that this happened. I didnt say anything until that evening when the kids went to bed. I got out of bed to sleep on the sofa and he came down asking to talk after a few minutes. He said sorry, i said sorry wasnt good enough and i was gonna stay at my parents and i wanted him out the house by tuesday night.

He then broke down and apologised and said he wouldnt have gone through with it and that he didnt knw why he did it. He said we were drifting and that i always seemed annoyed at him about something and he didnt think. There was lots of tears and apologising and saying he didnt want to lose me or the kids and didnt want me to leave. We had a few days of tears and talking. We have somewhat worked it out and are making an effort in the relationship. We have had tears and honesty and i told him there wasnt another chance and he had to talk to me, he promised it would never happen again and that he feels horrendous and that he is an ***** and didnt think about other things, like i could run into her in our local shops etc. He has unfriended her on facebook and deleted the messages, i also asked him to block her which i think he did.

Where the advice/support comes in please - i cant talk to anyone as i think they will hate him as we have the same friends, or tell me to leave but i want to try and work on it. How do i trust him, im worried everytime he is on his phone about what he is doing or even what he is thinking. He seems to be doing fine, acting "normal", he says he is doing it for our daughter so she doesnt see him upset which i do understand but im afraid things will just be back to normal and something happens again. He is trying doing little things, like waking at 9am instead of being in bed till after 11am but i feel like i am the one making more of an effort, trying to plan time to ourselves as we both work and if we arent at work we have our daughter as she is at home all the time. I really dont want things to go back to the way they were.

I would really like some advice from someone going through similar please and without any nasty comments as i just need someone to talk to and some help. I am in a fragile place right now and i couldnt handle any nasty.

If you get this far thank you so much for reading