Is this a thought terminating cliche

I think it is a thought terminating cliche. 

Just for reference there is also accident fallacy and oversimplified cause fallacy .

And before you reply anything to someone telling you that ONLY YOU are "responsible", ask them what they mean by "responsible". If someone is chasing me with a knife and I start running but can't escape and I'm cornered but I have a gun, which by the way all along agonizingly tried not to use but being cornered I choose to use it (cause I will not risk fighting someone with a knife), am I really responsible for shooting? Really? The fact he's trying to kill me and I have no escape makes ME "responsible"? The other person has nothing to do with it? No responsibility at all? BS...

Yeah, it's not a fallacy, more like a cliché and, more broadly, a way of thinking - the idea that only you are responsible for what you do, and so shouldn't blame anyone else.

I'd also argue it's wrong, because it ignores relevant context (e.g. financial circumstances, geographical location etc), but there's no argument there.

I don't know what I would call that; I guess it depends on the context.

In the legal arena, people are held accountable for their actions. However, in the philosophical arena, there are some who argue that free choice is an illusion.

In the first context, I would argue that a person who gets drunk and runs someone down with his car needs to pay a penalty. In the second context, I might ask why he was driving while drunk to begin with. (That doesn't necessarily mean he should get away unpunished, however.)

I find it to be more thought-provoking than terminating, especially in the context of an immature personality whose default position is to shift blame on everyone and everything else. We've all met the petulant child or the wily sociopath who sloughs off any personal responsibility and is always the victim of someone or something else.

It does not preclude mitigating circumstances, but that's not the point. It's an excuse, but it does not detract from the essential truth of the idiom. The fact that the train was late might contribute to the reason for being tardy, but it does not negate the essential truth of taking responsibility for one's actions. 

I doubt whether it qualifies as a cliché in the traditional sense because there is a solid truism behind it. Clichés are expressions that are so common and overused that they fail to impart any real impact on your sentence.

Taking responsibility is a characteristic of maturity and self-awareness and when directed at someone who falls short of the mark it might be a timely catalyst for both reflection and correction. 

Maybe a more useful saying is, "You are responsible for your choices." Whatever the circumstances, you are responsible for how you respond to them.

Your behaviour will almost certainly be informed by your personal history, shaped by the current context and limited by your capabilities. An action that might seem immoral or unreasonable in isolation may well be virtuous and sensible given the circumstances.

I removed the 'only' from the statement as responsibility can be shared. If a parent brings up a child to be a criminal then it would be unfair of them to solely blame the child and discount their part in it. But this wouldn't excuse the child's choice to follow a life of crime.