Is my husband cheating

My husband for the past 3 months has been guarding his phone when he never did before. He got really aggressive when I picked it up n accused me of not trusting him. Ive seen a couple of pictures of one of his work colleagues on his phone and now he’s told me he is staying out all night in a hotel sharing a room with 2 male colleagues for a post Christmas night out. I’ve confronted him and he says nothing is going on. He has mentioned this one girls name from Work a lot. I’ve also seen a couple of emails from them both for work related subject but he calls her babe n puts 2 rows of kisses. Am I being paranoid or his he cheating. We have 11 month old daughter I have suffered from post natal depression n wen I confronted him he said he feels like I’m pushing him away but denied any wrong doing 🙁