First of all I would like to welcome you to the Healing Well forum. I am glad you came here for advise. There are a lot of understanding people here.
I want to say that with the bad experience that you had a few years ago is still interfering with moving on. Maybe you should embrace it and work on that. It sounds like you are not quite ready to date yet. I think you should wait until you feel comfortable with the situation, instead of trying to do something that you aren't ready for yet. Have you talked to a therapist about what happened?
Why did you feel like you needed to stay the night with the guy? It sounds like he had the wrong impression about you. You didn't owe him anything for not wanting to get serious in a relationship. Start listening to your better judgement. You are a special and wonderful person and you need to be selective about who you go out with. If you want to wait to have sex, I think you should do just that. Don't feel you have to do what your peers are doing. Everybody has a right to make their own choices in life. Be careful and don't rush into anything just because somebody else is doing it. Take things slow, you will know what is right for you.
I hope that this helps you some. You really have to be careful with things of this nature.
fibromyalgia, chronic fatigue, clinically depressed and allergies