My husband and I separated for more than a year now. We are legally married and have three kids. The separation is not yet legalized (we do not have divorce in our country). He only forwarded financial support two months after we separated, after that, he sent me a message telling me that I won't be getting anymore money from him. If I were to file a case, how much child support can I ask from him? I learned that he is now living with a new partner and they already have a baby. They are living in our house (although there is no legal title for the house and lot, the lot was granted to us by his parents, and the house were from out joint income).

Support is determined by the law of the nation where the divorce and support is issued.

In the US, you may be able to ask for 1/2 of all property gained during the marriage,
Spouse support will depend on many issues of income of both parties, education and more.
Child support will go to the person with custody of the children. With three kids, at least where I am from would be about 30 to 35 percent of total income.

But other areas differ greatly.