financial support for my 7 years old son

What is the legal action for my husband that does not support my son, we are married and he currently living with his mistress, I tried to seek help in our brgy,but nothing happen to my complain.until now he did not provide support, he said he support our grandson who are sick,So he cannot give me support,Within 7years i just recently seek help from him because in hard economic times,
What is a case that I can filed to my husband and to his mistress.?can i still filed the case against them even they live in for too long ( more than 7 years)? and what is the proper procedure for this if i file the case? expecting for your
response..and more power

send a demand letter then file a complaint for economic abuse at the prosecutor's office.