my "ex" is threatening me

Hi. I am still "legally" married. But my husband and I no longer live together. We parted ways in 2006. He was a drug user and I was a battered wife for almost ten years.
We had three kids then.
After the "separation" ....I had a serious relationship with another man and got pregnant.

Now my "ex" husband threatens me that he will kill me and the father of my youngest child because, according to him, what I did was unacceptable.

What right does he have now? He does not support his kids since we got separated. Well, he give 500 pesos once in a blue moon.
He keeps on sending me text messages threatening my life.

What shall I do?

on this child's birth certificate, who is listed as the father? how old is the child or how long has it been since his birth certificate was filed?