How Do I Keep This Going?

Hey all.

I met this 18 year old girl on friday. Basically, a friend and I approach these two girls. Within minutes, we were making out. I was fingering her, she was giving me a handjob. I kept trying to separate her from her friend, but she was giving me tons of last minute resistance. We hung out for probably around 30 minutes. I finally started making headway (she was telling me to convince her), but then my friend said something stupid. He talks a lot and, sometimes, he just has these string of consciousness moments. Basically, he told the girl that she had no morals for doing what she was doing. Obviously, this is one of the worst things you can say to a girl and she flipped out on him. I tried to calm things down, but she wasn't having it and told us both to f off and left.

I texted her the next day, basically apoligizing for what my friend said (not something I would normally do....but even I was a bit offended by his remarks lol). I wasn't expecting her to answer, but she did. We texted a few times back and forth. I invited her out for the night, but she said she was staying in to study (which is consistent with what she told me the night before before that whole situation happened). Still, her text responses were lukewarm and spaced out.

I'm thinking about texting her tomorrow with something playful about her test. My text game is pretty bad though and I believe that I've lost many girls with it. So I'm definitely open to other opinions. Should I text her on monday with something like I said? Make it more sexual? Wait til the weekend to text her and invite her out again? (Unfortunately, hanging out during the week isn't an option. I live far away from the party scene and have a very demanding job that keeps me very busy during the week.)