If Donald Trump loses, the only one to blame is Donald Trump
If Donald Trump is the Republican nominee for President and loses the November election, the only person he has to blame for that loss is himself. If he loses to Hillary Clinton, then he deserves to lose to Hillary Clinton.
It is not Republican voters' responsibility to automatically vote for everyone who has an "R" next to his name. It is the candidate's responsibility to convince voters he is the better candidate and then to convince those voters to actually show up and vote. If Trump does not do that, then he does not deserve to win. At least in my case, Trump has absolutely not convinced me to vote for him, and therefore he does not deserve my vote.
And let's leave aside the nonsense about "party loyalty" and how I am "helping the Democrats" and get back to the real world. It does not matter what I do. I have a blog with a low readership and I have little influence even in Monroe County politics. No one is going to change his or her vote based on what I do or say. That is up to each individual voter - and, again, it is Trump's responsibility to convince those voters that he is worthy of their vote.
If Trump (or any other candidate) wants my vote, it is that candidate's job to make his case as to why I should vote for him. Trump needs to convince me that he no longer holds the Leftist views he has advocated for decades, that he is of sufficient moral character to be President, that he will not further corrupt the Republican Party and turn it away from conservative principles, and that he has the temperament and professionalism needed to be the President of these United States. Here is a spoiler: He will not and cannot do that.
Finally, if I vote for Donald Trump after everything I have said about him than I will be a liar and a hypocrite. I am not going to sacrifice my integrity to add one more vote for someone who will win Indiana and lose the general election regardless of what I do. If I become a liar and a hypocrite by voting for Trump, everything I do and say will have greatly diminished value, because I will have proven I am not trustworthy. I value my principles and my integrity far too much to throw it aside for the sake of party loyalty.