As in a death? or other? If the former you will need time to grieve and it takes a substantial amount of time take each day as it comes, remember that people just want to help

no i just am a fuck up and ruined the best friendship i ever had

ok, i see. I won't ask how you messed up etc but you have noticed yourself that there has been an issue, this is a good first step, the 2nd is to reach out and apologise to the person or people involved, it may take time for them to forgive you but i once lost 2 best friends and after years of reflection and a major attitude adjustment i reached out to them and apologised, thankfully they both accepted. there might be a rare chance they might say no, but it is very rare, if that happens then you will have to accept it and grow from this experience, as that is what life is, just one massive long learning experience.