Hi, I'd like to help you with your question.
There is nothing wrong with you. What is wrong is what happened to you. The abuse has caused you to react to sex as if you should be always available to any man who wants to be with you. Your ability to shut your feelings off during sex is a coping mechanism that helped you survive the abuse you suffered through.
Your reaction to meeting men is actually very normal for what you went through. You had to survive, you did not have a choice. So you keep yourself sane and ok, you chose to let the abuse happen and shut your feelings off. It helped preserve you as a person and helped you cope. It actually shows strength because you found a way to get through.
What you are struggling with now is that you no longer need these coping mechanisms. But since you have not worked through the feelings left from being abused yet, then you automatically react the way you used to.
Therapy is a great way for you to address your past and develop better ways of coping. If you cannot afford a regular therapist, you can contact your local community mental health center for low cost help. Your local United Way should be able to refer you to the center closest to you.
You can also pay out of pocket to some therapists. There are a few who will work with you on cost so you do not have to pay full fee. This would require you to call around to therapists in your area to ask, but it may be worth it. To find a therapist, you can search on line at http://therapists.psychologytoday.com/rms/. If you attend church, you may also be able to find low cost counseling there.
You can also use self help to work on your issues. Here are some resources to help you:
The Courage to Heal 4e: A Guide for Women Survivors of Child Sexual Abuse 20th Anniversary Edition by Ellen Bass and ***** *****
The Sexual Healing Journey: A Guide for Survivors of Sexual Abuse by Wendy Maltz
The Survivor's Guide to Sex: How to Have an Empowered Sex Life After Child Sexual Abuse by Staci Haines
You can find these books on Amazon.com or your local library may have them for you.
I hope this has helped you,