Sorry to hear that your first impressions were like that. I had the exact same experience when I started this game.
When I was first invaded, in the depths, I had the drake sword and a phantom with me, we barely could defeat the slimes, and the invader shows up with a lightning zweihander, he one shot me with a running R1. Welcome to dark souls I guess, after that all my PVP experiences were in the forest, where you imagine to be the worst place for a newbie. But after meeting people in this forums, I learned how to proper "duel" with rules, as such: no backstab, no healing, etc.. I made my first PVP build and multiplayer got fun at least. After some time, I decide to make a darkwraith and began to invade other people in multiple areas, sometimes I had to fight 3 people at once, sometimes I had to murder a newbie, but a lot of times I had fun trying (and killing!) hosts and phantoms! Specially if after I made a dedicaded darkwraith build (not so overpowered, but also not weak against 3 people).
So my advice is, do not quit yet, try mutiple ways to PvP. I'm playing this game for 2 years and I can still find new things to do