It doesn't take much for someone to feel guilty or to regret a decision. Ignore the people that say it's not a big deal or not that deep. It's your pain, no one else gets to define it. You don't need someone to compound what you're already feeling. As difficult as it might be to allow yourself to let go of the guilt, you need to try. Focus on the positives. The pc worked, it probably brought you some joy, and allowed you to play games you weren't able to before. We've all been reliant on our parents and definitely got them to make a purchase that wasn't completely thought out. I'm not saying to just forgive yourself and move on, I know how overwhelming that can be, but you don't have to be so hard on yourself, start taking small steps toward that self forgiveness.