You get to decide if both poisons are equally bad or not. If one outcome will be better than the other then you should try to bring it about. It is not a moral obligation to do so in the same way that you need not say anything to the kidnappers when they show you the two poisons, of which you will have to ingest one. If one is deadly and the other only sickening then you ought to choose the latter. Before you tell them "ipse venena bibas", or "drink your own poison", remember that the poison will be forced down not only your throat but everybody's, even your children's.
In fact, our situation is worse than a hostage crisis. Were it only that, you could try to reason with or persuade your captors. Rather we are hostage to a stampede numbering in the tens of millions who will force us down one road or the other.
Yes, of course, you are insulted that these are the choices. Perhaps you are mistaking your vote to mean that you think a particular candidate ought to be President. Instead you really are just choosing between one of the possible outcomes, one being better than the other(s). Are you thinking that your vote somehow morally unites yourself to that candidate? You will take upon yourself the moral character of the qualities or policies that motivate you to vote. Voting for Donald Trump would make you guilty of sexual assault if that would be why you are voting for him in the same way that voting for Hillary Clinton because she vilified her husband's alleged victims would make you guilty… something terrible. Both scenarios are highly unlikely. Voting for Hillary Clinton does make you guilty of murder if abortion is one of your reasons for supporting her.
If you are insulted by the menu choices then it might be time to reconsider this method of choosing. Some of us are insulted by voting in the first place. Adults do not make serious decisions by taking a poll of all parties affected. Why would we expect a popular vote to have a good outcome? Why would we expect more people voting to yield a better outcome? Why would we anticipate anything other than not only a worse outcome but also worse choices next time around if we do not expect voters to become more intelligent and more virtuous? I digress… but only in the way that a hostage's mind might wander. We should consider more energetically the democratic crisis that afflicts us and we should do so long before the next election cycle. In the meantime...
This vote is not a discernment of a free moral act. When we are freely choosing we always are able to choose good. We always must choose good. We are not in that kind of situation here. Consider King David before the LORD and having to select from among three punishments: three years of famine, three months of fleeing an invading army, or three days of pestilence (2 Samuel 24:13; 1 Chronicles 21:12). Avoiding punishment was out of the question. In that case David was not just before another man but before God and so knew that he had to reply and choose the punishment that would befall him and his people.
I contend that this vote is a choice between two poisons. One of them would like to bring about the end of authentic Christianity. The other is simply disgusting. One intends to ensure that abortion, even its most brutal forms, remain legally protected. The other wants to defund Planned Parenthood. If the abortion business had nothing at stake in this race then why would Planned Parenthood give Mrs. Clinton a 100% rating and Mr. Trump 0%?