I cheated on my ex, but I regret it and I want him back. But he is courting someone else. I think the reason why he found another immediately is that he wants to show me that he can find others and that he doesn’t want to appear fragile to me. What should I do?
You are assigning your own feelings to your boyfriend. You decided to see another guy and your former boyfriend decided that he would rather date another girl as a result. Dating carries no obligations. Each person is free to make their own decisions and with those choices comes the responsibility to accept the consequences.
You can tell your former boyfriend that you realized you made a mistake and that if he finds himself looking for a girlfriend, you hope you’ll be available. In the meantime, you need to see if you can find another young man who might make a good husband.