Husband cheating???

I'm posting here because I need to get this out of my system. Can't tell family or friends but I can't keep this in anymore. So my husband had left a few days ago to his sisters house and spent the whole night there. I woke up at around 3 am and decided to go on his IG. Mind you, i had never done that before. So I logged in and was going through his feed and I clicked on his messages. I saw a message from a girl that seemed he had been messaging the same afternoon that we were both sitting on the sofa watching tv. He had been laying the opposite side of me so I couldn't see what he was doing on his phone; which I've never really cared because I "trusted him". So I saw that he had messaged her to ask if she could talk and this message was sent right after he had left to his sisters house. I flipped out and decided to check the list of calls and saw he had been calling her for quite some time at 3:30 am!! The time he gets to work right before he clocks in. He had also been calling her on the way home from work. And the times I wasn't home before he'd go to bed he'd also been on the phone with her for hours upon end. Not only did I find out he was talking to her so much. I also decided to log in to his iCloud through my laptop and on his notes I saw on the deleted file a message he was going to send her saying "I just want to say it was a pleasure hanging with you yesterday. It kind of feels crazy like how you say the line is being erased between us. I feel bad because I like come on to you jokingly but but I really don't know what you actually feel about that. I know we didn't mean for any of this to happen but it kind of is...."

At this point I honestly feel betrayed. I confronted him and he said there is nothing going on and nothing has happened. And like I told him maybe nothing physically but emotionally and/or mentally it seems like it did. I feel hurt and betrayed that he never has time to have a conversation with me. He never has time to hang out with me. Yet he spends hours upon end on the phone with this stranger which he says he has nothing with??

To what he said it's just the girl his friend at work had hooked up with and she ended up messaging my husband because she needed someone to talk to after she got dumped?!