long story short, my husband of 5 years has been training in the military academy for 3 years Monday to Friday in a class with 45 guys and 5 girls. Not until the final year he started dropping one of the girls into convo often and I didn't worry as I thought she had a boyfriend and I've never not trusted him before. He uses whatsapp groups a lot to talk with his colleagues over their studies and projects etc. Our son was born in August 2018 and two weeks after the birth we went out to eat with family and he kept his phone upside down all the time on the table, the baby was crying so husband got up to go change his diaper and I looked at his phone, it was a message from her and she said how she felt sick and was tired. seems innocent but why the need to tell my husband that on a Friday night. I left it and I was burning with curiosity all week. at the weekend when he came home I went to the bedroom and his phone was charging, I needed to know so I checked and he had a convo with her in a group chat, but they were the only two in the group, the others had left. so it looked really suspect liked he'd attemoted to hide it, she'd send a picture of her and her sister at the beach (why?) it was quite flirty, heart emojis (more from her) she asked if he wanted to meet for a drink and he said he couldn't, she didn't invite me, I was furious and confronted him immediately..post partum hormones raging. he claimed it's nothing and she puts hearts with everyone she talks to, and that if he had anything to hide he would delete it. I have no solid proof, so after a long night I demanded he cut contact unless it's about work. So he said he'd told her and she had said she would not message him anymore and that she laughed about it because they are just friends! it's not amusing to me! A few weeks later I'm sat beside him and an Instagram dm notification pops up from her. I ask to see his phone and he shows me a meme she sent to him about physics (which they study) not exactly flirty, but why my husband when there are 48 other people in their class? I just rolled my eyes and we didn't talk about it because we have a baby and the stress is too much. But I was angry that she clearly didn't respect me and continued contacting him. Either that or he never did tell her i saw their whatsapp convo (so many doubts) He said it was pure cooincidence that she sent him rhat and he never expected it because they don't message anymore unless it's work, but it was super awkward as he was just showing me something on his phone and it killed our sunday afternoon. I since learned that he's changed his password, we both used to use the same one on our phones but now it's finger print. He was annoyed I went in his phone, but he would do the same. and him changing the password only makes me more paranoid. so anyway it's always in the back of my mind because it still feels like he has a secret to hide. but I'm the crazy wife because I checked his phone and bring it up when I feel he's being distant. Part of me feels like he's scared I'll divorce because we just had our son and maybe he thought he could have a secret affair and i'd never find out and too stupid to prove it (best of both worlds) a lot goes through my mind when I'm up at night with the baby. So as he's concluded his training we decided to move away from the city, and I found out she's working close to where his new job is. It feels like she's haunting my marriage. I don't know how to carry on like this or even prove anything? curious if anyone else has a gut feeling or experience about it?