Word of advise !

So I wanna know what you guys would’ve done in this situation , I’m pretty much younger than my child’s father and before our baby was born he told me about his moms controlling behavior & how she did it to his ex (has a son with her ) but she allowed her to do these things because she respected her , now to keep a long story short his mom passes her place all the time by asking for my child’s importance documents saying I don’t need them (we live in another country ) and she will keep them in case anything is to be done important documents like for example ssn … anyways , she calls and basically demands me to do things & often times her son and I never even speak about the things she says to do . I spoke up to her and let her know she doesn’t get to cross certain boundaries and that her son and I will be the parents to our kid , her son got mad that I said this took it as I was disrespectful to his mom and say “permanent cut off “ and only to deal with him as it pertains his child , what do y’all think ??? 🤔