Dude, I have a friend who was suspecting his wife of cheating with a coworker, like you said, but just by chating and spending a lot of time with him. He confronted her and aked for conversations of whatsapp and didn't find anything, just casual work conversations. Later, when she went o a training, she forgot her whatsapp web open on her home laptop, he opened it. When the chached messages started to dissapear, he disconnected it from internet and read th remaining discussion which gave him a clue that she could be cheating. She also had her google account connected to her husband's phone. This was the first clue, that the conversations were deleted by her. While she was at the training, for 2 weeks, she didn't want to come home for the weekend because she said that is far away. So, he wanted to surprinse her because that weekend was their aniversary and he went to the hotel where she had the training. He called her and she didn't answer. He asked her colleagues about her and they told him that she went home for the weekend. Then, he opened her google account and her location was live. She was at 20 km of the hotel, at another hotel for the whole weekend. He then confronted her and, with these evidence and they are separeted now.
My point: confronting without real evidence may not lead to something because she can delete those messages. You first need to make a research, and don't look in her phone because she will become suspicious. You need to find another way, to see what she is doing.
