Re: My life is over !
First of all---are you 100% certain that it's your child? Before going any further with her, insist on a DNA test.
Even if it is your child, you don't have to marry her. However, you do have to be involved in your child's life (if it even is your child). Staying involved is especially important given that the baby's mother is a psycho. Be prepared for the possibility that at some point you may have to petition the courts for full custody of the child. At the very least, expect to regularly pay child support. I can't stress this enough --- if it is your child, you must stay involved in the child's life. That poor child will need some stability---that's why I say be prepared to push for full custody at some point.
Stop thinking that your life is over! Yes, if it is your child, your life has forever changed. However, you don't have to go through with marrying her.
And, please, for your own sake, get some counseling. You need to find out just why you got so attracted to someone like her. Counseling will help you gain insight into this and help you learn not to once again get attracted to this type of person.
Good luck and get going! I can't stress it enough --- insist on a DNA test! Also, I know that this is going to sound preachy but, in the future, if you don't want an unplanned pregnancy to occur---please use a condom!