Telling my son he’s autistic

Hi I’m new here and looking for some advice my son who is 12 has just been given his diagnoses after nearly 3 years on the cdact waiting list, also the wait before his actual assessments and observations before going into the cdact list do it’s been a while before reaching this stage! He understands that he was assessed but he’s very much things are black or white, yes or no so refused to accept there was a possibility he’s autistic but now we have his diagnoses I’m worried how to tell him, I know he’ll always remember the day he was told so I want to get it as right as I can though I know sometimes there’s no right or wrong way but I just feel it’s really important I can explain as best I can. We’ve always known deep down and it’s been more prominent as the years have gone on. He’s at a really tricky age trying to identify himself trying to express himself and just become a teenager he has a lot going on in his wee head as it is, he with anxiety issues he has a lot of facial and vocal twitches/ticks he can get very loud though hates loud noise unless he’s making it, he is going through a lot at school now he’s at high school with bulling it’s been awful for him but lo always be his voice, stand up for him and be his biggest supporter

! If anyone has any advice on something to say and not to say to make it more comfortable I’d be really grateful :) 

thank you xx