Am I crazy for not trusting husband...

After a great vacation approx 6 weeks ago with my family and no cell service we got back home and my husbands mood shifted completely. He is attached to his phone 24/7. Grumpy and short with me and the kids, who he only sees for an hour a day. He makes me feel like I don't do anything right and questions how I do everything. I try and tell him how he making me feel, he either doesn't listen or denys that he does anything or says he is just joking around and I need to lighten up. Now my 5 year old is talking to me the same way her dad does. If that wasn't enough 2 days ago I picked up his phone thinking it was mine. They look the same, and saw a message in his lock screen from a woman who I have never herd of. I tried opening his phone and he had changed his password. I don't have the time or energy to deal with this so I just asked who she was. He said he was talking to her for marriage support and it was nothing. For the rest of the day he was the perfect husband even my sister said he was acting different and I didn't tell her what happened. Yesterday I saw another message for the same girl but it didn't look like advice. I took his phone and called my sister to calm me down before I talked to him. We had issues with inappropriate conversations 7 years ago but got through it, got married and have 2 kids. When I came in and asked for his password he was on his computer and when I opened BBM the conversation was deleted. He says it was harmless and he did nothing wrong. If he did nothing wrong why is the conversation gone? He said he regrets going to someone else and not me to descuss our issues and doesn't want to loose me or his family. In the past he would get angry and pass the blame so I believe he wants us to work out. All I can think of is what was he saying that he had to make it disappear instead of letting me see it. How do I ever trust him? We had issues before this weekend but this is all I can think of.