Welcome, Joe.
There's a knee-jerk phenomenon which assumes that:
Republican=Conservative Stalwart of Strict Constructionism, and
Democrat=Moonbat Liberal Communist.
Neither is true all of the time. Lately, neither seems true most of the time. There are several Republicans who are hostile to the 2nd Amendment, and even more who just don't care one way or another about it.
It's become obvious to anyone who pays attention that the current generation of Democrats are largely pro-gun. When our Attorney General decided it would be a good idea to pontificate on renewing the Assault Weapons Ban, "conservatives" ran around screaming, and nobody seemed to notice the fact that 65
Democrats sent him
a letter warning him against doing so.
H.R. 1399, also known as the District of Columbia Personal Protection Act, recieved the blessing of 85 Democrats.
I've seen the hostility towards anyone who admits to voting for Obama in the last election on several different boards, and frankly, it's immature and uncivilized. While I do regret your choice, it's still a free country, and you had a right to make it as you saw fit. If you support the 2nd Amendment, there is no reason you should not be made to feel welcome.
The preservation of our 2nd Amendment rights lies with gaining the sympathies of those in the middle, and that includes people who identify themselves as Democrats. Calling them "trolls" and running them off doesn't do anyone any good. We should be working to convince and convert people, not insulate ourselves.
Lord knows, I've been teaching alot more Democrats to shoot since last November than I have Republicans. These are the folks who go home to their families and friends and say, "hey, this is actually a fun hobby, and those gun guys aren't the bunch of loons we've been led to believe they are."
Oh, and to answer your original question, the best way is to enroll her in a class. Heck, go with her. It never hurts to have a refresher. Education goes a long way towards making someone comfortable with the unfamiliar.