Dale, I am sorry your mother was unable to tell you the truth about sex.
There is nothing shameful about the male or the female body and nothing wrong with sex. Erections are a normal part of every male's development.
I think your mother transferred her own thoughts and fears about sex and sexuality to you, and you have been confused ever since.
The girls that burned you did not do it because you were bad or because they hate men's penises. Unfortunately, you will be unable to find out the real reasons why they did such a thing to you because so much time has passed.
Now you must move forward and find the freedom you deserve. A good therapist can help with that, Dale. S/he can help you discover the truth about things so you can put this issue behind you and experience what life has to offer before it passes you by completely.
Your mother has robbed you of many years of joy. I hope you can forgive her for her mistake and wish you much future happiness.
Good luck.