I can't believe you're having a conversation like that over instant messaging. It's like you're trying to scare this girl off.
Edit: To elaborate, any conversation topics that could lead to arguments shouldn't be had over email or IM. If you have her phone number, why didn't you talk to her about this stuff over the phone. Also I think you were being too open. Telling the truth is good, but do you feel it was necessary to let her know that there's a girl you had sex with that you're planning on continuing to see. She was trying to make you jealous with her Spanish "I love you", but it seems like you were doing some of the same by talking so openly about this last girl. Also, continuously talking about her sexual history and making it seem bad is going to make things harder for you if you still do see her. Knowing you think negatively of her sexual past, she's going to be more guarded about having sex with you. I think most of what you said to her is true, but saying it also hurts your goal of getting with her.