I feel I need to sexually assault my ex.
Why do you want to sexually assault your ex?
Because I'm desperate and I feel like killing myself
That is completely wrong and totally immoral. Sexual assault is always wrong and you should never do it to your ex, or to anyone else. There is never a reason to force sex on anyone.
I agree, but I'm going to do it anyway.
You should respect that the relationship is over and seek medical attention. If you are suicidal or feel the urge to hurt someone you should get help immediately before you act on it.