You'll be scared for a while. It lessens as you go through with the campaign, though the occasional beady-eyed large person staring down at you saying 'Waita minute ain't this about HOMO-SEXUALS" can make your stomach curl up and die. But YOU won't.
Yes, our opponents in Arizona directly lied and said our campaign put forth "distortions" and misinformation, when in fact, we simply explained to voters everything that the amendment was going to do according to what the text of it said. It was a very brief text, which our literature printed out in bold. We just showed it to people, with a sentence or two explicating how "no legal recognition for unmarried persons shall be created or recognized" could play out state-wide, and already had been playing out in states with near-identical wording (Ohio's amendment was almost verbatim the same as ours). Given that information, voters decided the amendment was no good for Arizona.
You MUST obtain the text of this legislation or initiative that you are opposing and inform yourself exactly how PA's particular amendment would play out if it passes.
No, having DOMA on the books is not enough for our opponents. It is easier to overturn a legislative statute than it is to overturn a constitutional amendment - that is why they push so hard for the amendments to set gay couples back another generation.
As for people opposing marriage equality: I forget the exact poll numbers, but when Arizona started fighting this campaign 2.5 years ago, those supporting marriage equality were a fairly small minority. The poll numbers changed - okay, I can't remember if this was regarding marriage equality specifically or regarding issues like employment non-discrimination, etc - but I DO recall that poll numbers changed, and after the election was over, Arizona had seen an 8% increase in general support for LGBT equality since when the campaign began. Our campaign not only stopped the tide of marriage amendments, it increased local support for LGBT equality in general.
You'll likely find that working on this campaign can bring things a good way forward. Your campaign needs to find the right message that is accurate and truthful AND resonates with PA voters. AZ's campaign hired a polling group to determine what our exact message would be.
Meantime, when you get down about your colleagues not supporting you, remember you have a whole entire cheering squad out here.
You are going to feel so good about yourself for doing this.