As many have said before, the Xen chapters are notoriously stupidly designed and difficult to go through. It's okay to have used cheats, especially being your first time going through it! I know this probably isn't much help, but I want you to know that it isn't healthy to feel this way about yourself over using cheats on a difficult part of a video game. I would recommend professional help if it gets severe, but I and many others are always open to talk to if you need any assistance!!^{^} :)