I’m so sorry that you lost your dad to suicide at such a young age. It sounds as though you had such a lot to deal with trying to support him with his depression, and very little support for yourself. You are absolutely not to blame for his death - his depression was what caused it.
It’s really important for you to have some support and outlets for your emotions, and I hope that it helps even a tiny bit to be able to share things here. Everyone here has lost loved ones in various circumstances and will understand some of what you are going through.
We had a user called @shizwhiz post a few weeks ago about losing their mum to suicide - you might be interested to read and reply to their post here: My mum took her own life and now I'm lost
There is also this conversation where you can find a user called @Tt951, who lost their dad at only a few years older than you: 24yrs old.. My dad died infront of me before Christmas
@anon94470799 has made some good suggestions for further support. There is also an organisation called Grief Encounter, which specialises in supporting young people with grief - you can speak to their professional counsellors by phone, email, or instant message chat.