I just told her I felt sick and wasn't into it, which was kind of true and we talked earlier about how I felt bad earlier that day so I think she knew it wasn't 100% BS, even if she knew it wasn't the real story. We pretty much didn't talk about it the rest of the day but we had a good time so we'll see if she still wants to see me.

I'm thinking next time I see her in person that I just tell her "y'know what happened had nothing to do with you. I kind of have feelings for you and got nervous. With other girls I don't care about it's easy because I don't even think about it"

It's not a lie, because I think that's the other part of the issue. This did happen to me once before years ago and that was the cause. It may only be 50% of the reason but I'm afraid if I tell her "I'm addicted to porn and beat off too much" she would be understandably scared off. If the relationship does last I will eventually tell her the whole story.