Hey it happens.
I so happen stopped talking to my friend, and we've been friends for a long time.
I stopped talking to her because I got busy with work and just not being home very long. I just got busy. Every once in awhile I send her a message on a social networking site.
There were also some other reasons I don't talk to her. She started rapping, and every time we talked she wanted to show me her new song. Now I'm not a rap person, not at all. It's not that I don't support her it's just that I wouldn't be able to enjoy it to begin with. It's like someone is running nails on a chalk board.
If I were you I'd just do my own thing as well. We've had our moments and months that we don't talk and then we start chatting it up again like nothing happened.
If your friendship has lasted 20 years it can certainly last this rough patch,
So take Cat's advice and stop contacting her and let her come to you.
Just another thing:
Last year me and my friend on 10+ years got into this weird fight, I didn't speak to her in a year and we just started talking again and we've both moved on from what happened.
So in short, fights and getting distant happen, but you'll get back together in no time