There might be a cause of action for what is called negligent infliction of emotional distress. However, this is extremely difficult to prove and you may have to prove some kind of physical ailment that is said to be caused by the emotional distress your past relationship has caused you. Typically you must show things like loss of sleep, stress leading to physical ailment, and most aflictions must lead to medical treatment. Further you will have to have a Dr. account for the cause of the ailment being the stress. Again, it is very difficult to prove and probably highly unlikely there is a suit there, but based on the limited info in the question that is the only plausible cause of action i can think of. Good Luck.
What are your goals in suing the other person? Sometimes, it's better to just move on.
Did the two of you lived like a husband and wife? If yes, you may be able to get some of the assets that would have been community property if the two of you had been married to each other. You would have to ask the court to determine that there was a meretricious relationship between the two of you.
Depending on your specific facts, there may be other legal options available to you. You may want to review your facts and options with an attorney.
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