There are no ethical choices under first-past-the-post voting. We must instead make a decision that reduces the most harm.
Yes, a million times this. Voting is just one small part of what we must do to fight for a better future. Giving up is not an option, there is far too much at stake. Vote, protest, occupy, run for office, take direct action, organize, and create a better world for the people who come after us. Solidarity forever.