How do I stop blaming myself for someone else's actions?

Tell yourself what you clearly know. It's not your fault and it's someone else's actions that caused the problem.

Think about how you feel about this. What would it be like to be the other person? Think about others.

Understand that you are not the center of everything and that not everything revolves around you. There are many external factors as well responsible for mistakes. Said that, think about about taking steps to avoid them in future.

Be sincere. Most of the people loves to know how the others are feeling about them. If it is a positive emotion, don't doubt, share your good feelings toward somebody could make their day better, could give them a smile, could help her with a struggle. If it is negative, then don't hide it, but don't use your words like bullets: be honest, but be sensitive. The other is also a human, a person with emotions, and you have to be careful without lying, is the best way to resolve a problem, rather than the silence when, behind this, are a lot of troubles that you aren't saying.

I feel like the best way to stop blaming yourself for someone else's actions is to know that you did not do those actions. That person acted by themselves in the situation. And that you are not to blame for the outcome of that decision making. I feel like maybe separating yourself from that 1 person could help. And just keep telling yourself I am not responsible for other people's actions the only actions you are responsible for are yours and yours alone. There is no way to control other people's actions. And just tell yourself that you are not responsible for this person and their actions