Until your system does anything useful with third party votes or couch-sitting, you go out and vote every time for whatever does the least damage to democracy. But don't disengage from the political world after the election. Between elections, you work to change the system. Find groups that tries to do this and volunteer. If you really care about it, you will need to dedicate your time to the cause, even though it might seem hopeless and may very well be.

I understand your situation sucks and you are tempted to say "Fuck the status quo" and desperately do something different in hopes that something will somehow change. But you know who do go out and vote, every fucking time? The racist assholes who would love to see Trump and his fascists cronies in power. And if that happens, it is game over. You will never get any chance to change anything, except from after a big traumatic event such as a big war ("civil" or otherwise).