Please don’t judge me I don’t know what to do

My husband of 17 years broke my heart and then obliterated it! Last year I had the strangest gut feeling my husband was cheating I had never felt this before as he never gave me any reason to and I trusted him implicitly he was my soulmate and we were amazing together, so I called him out told him I had these feelings he was cheating on me and I asked to see his phone, he never argued once and passed me his phone and I’m like ooohhh kayyy maybe it’s just me being stupid but no unfortunately my worse fears came true he had been chatting quite intimately with a girl Co worker for 2 years (he’s 43 she’s 19) talking about how beautiful she is her calling him pet names him making inappropriate comments about her bedroom and what she was wearing etc. it broke me completely I was literally at the lowest I have ever been. We agreed to work on our marriage so I stayed and things slowly got better, better than it ever was before tbh but I was still wary and over thinking played a huge part in my actions so whenever he left his phone unattended I would snoop, yes I know it’s wrong and I’m ashamed to admit this and nothing incriminating popped up until a few days ago where I found an encrypted file storage app on his phone, I work in IT so accessing it was easy for me, I cannot even begin to tell you the disturbing photos and images of a pornagraphic illegal nature that I found like it made me physically sick and now I’m just numb I don’t know what to do next I don’t even know who he is anymore like he’s a stranger to me. We have a family and I thought we had built a safe home life together but wow I’m just so alone and ashamed and embarrassed and horrified I don’t know what to do :(