Looking back over your previous threads, I think there is a large problem in your tendency to lay blame. If someone's needs don't meet yours, it doesn't mean that they are using you. All it means is that you're not compatible.
If you find a gap in what they want vs what you want, you end it swiftly and without blame or accusation. Just say to both him and yourself "this isn't working for me, I'm going to move on".
Never regret anything that has happened in your life. It cannot be changed, forgotten or undone. So, take it as a lesson learned and move on.