If you're having a hard time getting over someone, it's likely because you're remembering all the good times without the bad. Take time to remember why you broke up, so you can break through the fantasy.  Try writing about it. Journal about the painful memories you have with the intention of letting go of that hurt, too, so you can move on. You're relationship ended because something happened or it wasn't going well, and if you put that relationship on a pedestal of perfection, it's hard to get over it. One way to work on forgiving them is to remember the good parts of the person, too. Think about what made you like them in the first place, so you can think of them as a whole person who makes mistakes. It's only when you think of them as a fallible human being with both good and bad qualities that you can forgive them their mistakes.  Another way to work on forgiveness is to think about how you feel about what the person did to you. Think about how those emotions are affecting your life. For instance, if you feel angry and bitter, how is that coloring how you see the world? Of course, some "mistakes" are bigger than others. With serious issues like emotional and physical abuse, it's much harder to forgive the other person. Keep in mind, though, that forgiveness is mainly for your benefit; it doesn't absolve the other person for what they've done. Forgiveness is about letting go of the bitterness you have against the other person. It's hard to let go of your negative feelings towards the person if you're not willing to forgive them. You don't forget your pain, just that you stop harboring anger in your heart towards the person. You may blame yourself for the breakup, or you may feel the need to blame the other person. But, in the end, the fact is you just weren't compatible with the other person, and no one deserves the blame for that. If you had a fairly amiable relationship, try to remember that you were both trying your best to make the relationship work, and work on letting go of the blaming cycle....

TL;DR in Vietnamese:
Tự nhắc bản thân rằng vì sao mối tình của bạn lại không thành. Tha thứ cho người cũ để xua tan oán giận trong lòng. Đừng tìm lỗi trong sự tan vỡ. Tập thay đổi thái độ của bạn với quá khứ thay vì chỉ ngồi đó mong xóa đi quá khứ. Đến gặp chuyên gia trị liệu tâm lý nếu bạn gặp khó khăn.