Girl blackmailing to marry by giving suicide threats

Good Evening Sir/Madam. I want to discuss with you something. Few years back my one of the friend fall in love with one girl. But after sometime they (like 2 years) were living separately. Now my friend got married with another girl. But that old girl is now telling to my friend..."if you are not married me then i will suicide. And in my suicide note I will write your name". Now my question is how my friend can get release from this girl ?