Is it harassment that the ex-wife sends a message to harass her knowing that she hacked her phone?

Not exactly. Harassment is an act of offending or insulting others through physical or verbal behavior against their will. Texting and calling many times generally does not constitute harassment, but it is illegal. The Law on Public Security Administration Punishment stipulates that it is a violation of public security administration for women to sexually harass men. Whoever repeatedly sends obscene, insulting, threatening or other information and interferes with the normal life of others shall be detained for not more than five days or fined not more than 500 yuan. If the circumstances are serious, they shall be detained for not less than five days but not more than ten days, and may also be fined not more than 500 yuan.