Unfortunately, it's not a "red line in the sand," no matter how much you keep repeating it. While a majority of people in the US disapprove of Israel's actions, a tiny fraction of voters (less than 2%) consider it their primary voting issue, an even smaller fraction of that number would consider withholding their vote or voting third party over it.

While you may not like it, it's not the major concern for American voters. If you'd like to withhold your vote or vote third party about it, be my guest. The only likely scenario that would result from that would helping Trump get elected. If you're honestly concerned about Palestinians, you'd be wise enough to not enable an even worse situation for them. There's a reason Israel's leadership wants Trump to win and encourages the left to revolt about Palestine.

You're getting played by Israel, who is using your short-sighted feels to enable them to enact long-term reals, which in their case might very well be the full extermination and displacement of all of Palestine. To truly bring that into being, they, at they very least, need Trump to win. Fundamentally you are siding with Israel over Palestinians, and the immediate sense of moral superiority you feel about it is precisely how you're being manipulated.

Read your history. Using the left's lack of political pragmatism to aid in hard-right political takeover isn't new. Your Bush-ist "you're either with us or against us" simplification of the world and political calculus makes you an easy mark. You are, quite literally, a tool of Israel at this point.

And the best part, from Israel's point of view, is you get to feel good about it. Win-win (for Israel). You're trying to march Palestine right into the grave while telling them you're helping them the whole way.