If i understand correctly, you are still legally married, and you're in Doha and your son (how old?) is the Philippines(?) living with...(?) your husband?

I think the best way is to call up your Embassy and ask : you want to invite your mother and son to come and visit you, and ask what would be the procedure for your son to get a passport (?) or an authorization to leave the country with your mother. If the son is in the custody of his parents (or father), and if he's under-aged, someone has to sign off for him to go...? no? Please try the Embassy and let us know. Good luck.