Married man with 6 kids who abuses you financially
and physically is really a scary choice. Please try to find ways to get away from him.

Your ex has rights to have relationship with his son but he also has obligation to help you to raise this son financially.

Please don’t spend any money on these men. If you live in Kiribati in my understanding your country struggles economically. You likely have a nice job and you sound intelligent so it sounds like these men taking advantage of you.

Both men sound like bad relationship material and the married one is downright scary

How is police force and law enforcement in your country? Could you talk to a police officer about this man hitting you? They can hopefully help you to press charges against him. Hugs and please be safe