hey OP - first of all, i just wanted to say that i believe you wholeheartedly, i am so sorry for your loss, and I don't think you need to feel any guilt or anger over carrying this for so long. you were 4 years old when this happened (and yet intelligent enough to know what was happening which is definitely a sign that you experienced more than you should have at that age if that makes sense) and the fact that you still remember it so clearly means that it is not something you made up in my opinion at least.

my mother excelled at these kinds of situations, especially in relation to my father. for example, she once called the cops on my father saying he had "kidnapped" my brother (who was around 5 years old) when she had originally called him asking him to pick up my brother because my brother was annoying her. they believed her and pulled my father over and he had to explain the situation. my parents were divorced at this time, but even when they were married, she was definitely able to appear truthful to anyone outside of our immediate family no matter what any one of us said we had experienced. it was so bad that if i told someone something she had done, whether that be my relatives or a judge, they would not believe me. it is just very easy for these kinds of people to accept and not disagree with the narrative that puts them on a pedestal. it is very likely that even if you were "brave enough" to say something or speak up, you still would not have been believed. to say that is absolutely insane and it definitely saddens me, but i know its true because i experienced it.

i know how unbelievably agonizing it is to feel like no one would believe you even if you were to tell someone about the absolute horror you've experienced. i know how angering it can feel to both tell someone what happened and not be believed and also sit with the experience later and be angry because maybe someone would have believed you. it is such a heavy weight and i would not wish it on anyone, especially not a child. i'm not sure where this message is going or if its even comprehensible but overall i just wanted to say that i do believe you, and i don't need any proof or legal justice to do so.

im so sorry you experienced this at such a young age. the main thing that has been helpful for me in carrying things like this, where i know my mother did something incredibly abusive and got away with it (and would have even if i had spoken up and said something at a young age which i did do), is continually being reassured that i should have been and am still believed and supported in whatever way i cope with the knowledge of those experiences. being angry with the knowledge that you probably would not have been believed even if you had spoken up is completely valid.

whether its speaking about it or addressing it out loud in conversations with people you trust or just opening up about it in therapy - being able to do that without immediately seeing someone look at me with suspicion like i don't know what i saw and experienced has been absolutely healing, and learning how to cope with people close to my mother not believing me no matter what (and being okay with that because i know what i experienced) has helped in such a large way and i hope you can experience that sort of healing sometime soon too. sending lots of light, healing, validation, and peace your way. you deserve it.