I think this would more a phylosophical question.
Everytime you make a decision, every possible outcome possible could in theory, create its own universe where all those possible outcomes do happen.
However, I do not believe you are merely watching, you are making decisions, in a fashion that merely creates more universe everytime you come upon a different choice.
If you ask me, this sounds like an unpleasant inneficient way of handling quantum uncertainty principle.
To create entire new universe just to account for all the infinite choices we are faced with, not to mention all other factors that would get their own universe, makes you wonder what kind of use is there for all those alternate universe.
I am a big fan of ocam's razor, I'd rather believe we live in a universe governed by unknown laws, to which we postulated many intriguing theory, however, I don't think it is very likely that every possible options create its own universe to answer the question we ask when we say "what if?".
So, if any theory is valid until proven otherwise, you can safely postulate that until proven wrong, you are responsible for your own actions.
Furthermore, just try to imagine explaining to a judge why your view of the universe as a being with no free will is the reason you commited any crime... I'm pretty certain you'd face a very skeptic judge with a not too lenient attitude toward you.