How to deal with my PTSD diagnosis

When I was 18 I was sexually assaulted. I’m 23 now, and for the longest time I thought I was okay. I’d talk about it and be like “yeah that sucked but I’m fine” and I genuinely believed that. Well, yesterday I saw a psychiatrist, not for the first time but it was the first good psychiatrist I’ve seen, and he diagnosed me with PTSD. I’m still not entirely sure he’s right. I know I showed the symptoms but good god, people go through things much worse than what I did, and I feel like such an imposter having this diagnosis. Anyway, since then, I’ve been having a really hard time. I can’t focus, I keep crying, like full on wailing, and reliving this thing I thought I buried. And I just don’t know what to do. I feel so helpless and angry at myself but also the world and it’s so frightening and overwhelming. I just don’t know how to make it better. I keep typing things into Google to try and find answers but nothings helping. I’m also terrified that this is gonna last forever. I have a friend with PTSD and I’m not sure she ever got over it. She went to therapy but all that did was make it worse, so she stopped. I realize im rambling at this point. Has anyone gone through this? Is there something wrong with me?