I am tired of this

For almost half of my life I’ve been hiding my feelings and toughts inside me as I have no one to reach out to that I think would understand me even just slightly. I feel like no one cares and I am just abandoned in this world. The worst is when all the negative feelings and thoughts accumulate over time again and they starts to overflow and I can not pretend that they are not there anymore, I can not ignore them. Those are the moments when I can barely control myself and my thoughts. I am tired of this. I don’t know how to handle the situation. How can I deal with it alone¿