I'm going to leave my ex girlfriend after she attempted suicide
Why would you leave after such a traumatic event?
Because she is acting really weird
I think the weirdness is probably a symptom of whatever caused her to be suicidal.  That's some heavy stuff there though, and if you don't think you're capable of dealing with those kinds of issues maybe it really is best for you to leave her.  You might make things worse if you stay.
People change, if she wants to act like a looney, she can go fuck herself.
There are many reasons people become suicidal. Using the term looney to describe her is not okay. She's just a person who needs help.