I need to get rid of bad thoughts

Asalam alaykum everyone. My question is that I am always having doubts and waswash about everything, let me explain. I feel like shaitan has alot of power over me since I am always getting bad thoughts and shaitan is always trying to make me do bad things like look at wrong things and break promises that I've made to people and to Allah. and i am just always getting thoughts in mind that I am doing everything wrong and that I will never be forgiven and that I have no hope left. I always feel sad because of this and I feel like I need a way to be stronger against shaitan. Please help me.