I think I am depressed and have suicidal thoughts
Why are you depressed with suicidal thoughts?
I'm tired of everything in life.
If you are depressed and are having thoughts of suicide, then you experiencing a mental health crisis and are in need of help and support. You should contact a mental health professional so that you can start receiving treatment and be able to overcome those feelings. It will require work but it definitely is possible to overcome depression and suicidal thoughts and live a normal life again.
You don't understand, I'm just thinking about killing myself as a last resort.
It is never ok to want to kill yourself, you need to talk to someone who wants to listen and help you. Your condition doesn't have an easy remedy, but expressing it to others is a good first step to ease your depression.