You dont break their hearts.
Let them believe they broke your heart.
You can make a girl believe she is hurting you emotionally by not understanding the reason you are emotionally unavailable.
Tell her she is selfish.
All she cares about is herself.
Tell her she is so selfish to stop talking to you because 'youre emotionally unavailable"
Not knowing you didn't know how to show your love for her.
Then use 3 situations to back up your point.
It will become she left a guy that cares about her because she's selfish.
You will be the toxic person but she will be the one breaking your heart