I've never been against ACA. I have always supported the idea.
However, calling House efforts to block it unconstitutional is not true at all. Budgets MUST come from the House, according to the Constitution. Yes, the Senate can amend, but that's not the point right now - the point is the constitutionality of the House putting forward bills that don't fund something they agree with. The House was given the "power of the purse" a long time ago, which allows them to choose what to fund and what not to fund. This is all part of the series of checks and balances, and has been executed before - once to effectively end the Vietnam War. The reason the House was chosen is because it theoretically is more representative of the will of the American people - it has a higher resolution (more representatives) and a faster refresh rate (2 year terms); therefore, the intent was to give fiduciary power to the part of Congress that is closest to the people. (Yes, gerrymandering is an issue in practice, but that's the result of trying to game the system.)
Here's a great article that discusses this: http://www.heritage.org/research/reports/2011/01/hand-off-my-purse-why-money-bills-originate-in-the-house
So, for better or worse, it is decidedly NOT unconstitutional for the House to push for an appropriations budget that doesn't fund ACA. This is how it works as laid out in the blueprint of the countries government. Calling foul when you don't get everything you want isn't the way to go about it.
Holding the entire government hostage is the responsibility of BOTH parts of Congress, and both parties. Personally, I think that everyone sitting in office should be voted out as soon as possible. I don't care if the balance of power doesn't shift... I want future Congresses to see that playing ultra-partisan games won't be tolerated and has consequences. Big Boy rules there.