Please helpp

So when i was 12 i found out my dad isn't actually my biological dad..and when i approached my mom about it she denied everything and crashed out on everyone else and i only found out about that recently and there was a time i went through her phone which is wrong ik..and i found a voicenote of her saying that she once tried to tell my father that i know that he isn'tmy real dad and he said that he isn't ready to talk to me about it..i was 14 then..im 18 now..and i feel like i deserve to get to know my biological family..i mean eventually they have to tell me the truth...there have been times where i approached her in the past years and indirectly asking her about it and she would get defensive and say we might aswell take a DNA test..but last year December, her uncle approached me and told me that i cant meet my other family when im 30..it has to be now and he tried to speak to her and she told him that if they want to be cut off by her they should continue..my chat is if this wasn't true why are so many people older people at that..telling me all this..its getting so old and if anything god forbid happens to her and im stuck here with so many questions and she just wont be there to answer...should i approach them and respectfully demand answers or should i just burry it like they did??