I have an ex-girlfriend who always likes to harass me. What should I do?

Since you have no problem, that's her problem. Whatever you think, it's useless. You just have to do what you have to do, because you can't influence her. You can only try your best not to let your lover get hurt. This is what you should do.

Let her do her own thing! Everyone has his own freedom. You can't let your will be imposed on others, can you?

Good luck!