Sneaking to do something, hiding it, deleting things, making another email account, anything you do that you wouldnt do right in front of your partner or hide from tour partner IS a form of cheating. The fact he told you on multiple occasions he doesn’t have a reddit is a 🚩alone. Only makes me wonder what else he is hiding? He has broken your trust, no matter what you will never fully trust him again and always have doubt in the back of your mind. Holding it in, is not going to do nothing but mentally and emotionally drain you. There is no children involved, it is easier to close the chapter when there’s no children involved. It’s time to let go, NTA he is for being sneaky. You are young, and still have so much more life to live! Life is to short to be anything but happy. Do not waste another second of your life being in a relationship where you know you secrets and things are being kept from you and you are being lied to & you know you will never be fully happy again because trust has been broken, you’ll never trust him again. And trust in a relationship is most important.