Grandma is overfeeding my 2 week son!

I really need some advice here. This is son's father's mother. Me and the father technically never had a real relationship and don't always get along the best. He lives at his mom's with all of his many siblings even though he is well into adulthood. Mama's boy I guess. Well his mom has overfed my son since day one in the hospital. Even the nurses there would comment that she was feeding him too much. I would have just fed him and she would come in and claim he was hungry and feed him every hour. It has only gotten worse since then. I gave them an overnight for thanksgiving <a href="https://play.google.com/store/apps/details?id=com.glow.android.eve">eve</a>. Even her own sister said she is overfeeding him. 4oz every 1-2 hours. A whole can of formula in less than 24 hours. I get home with my son and now he will cry for a bottle every hour even though i know he is not hungry, he won't settle down no matter what i do unless he gets that bottle. And he spits up a lot afterwards. I have been up all night with him because if i put him in his crib he starts spitting up so i have to hold him and watch over him. I am frustrated and angry. She thinks it is funny and nothing wrong. I tried talking to my son's father and he cursed at me and said he is eating and him and his siblings turned out great. I am thinking of getting legal custody done at this point and not letting him visit anymore over there until the legal agreements are in place. Any advice??