You see my friend was dating this girl and he broke up with her for some one else... Well right after they broke up we had sex 2 or 3 times one weekend... Now they are back together and she might be pregnant with his kid but says she wants me... What should I do?

Does your friend know what happened? And are you sure she is pregnant with HIS child?
If you are truly a friend - you should just leave her alone. If they don't work out - then you may could start a relationship, but know that you probably will lose this friend either way.

Yea... I'm trying to leave her alone its just that she keeps calling me up and saying how he does her wrong crying that she wants to see me... I have said no numerous times but said yes just as many I fell like I am falling in love with this women but... The situation is just really bad any ideas how I can get out of it?

Tell your friend what happened, its not fair on him not to know.

The first thing, like said above, is to tell your friend. You can not "save" this girl from a bad relationship. IF she feels like she isn't being treated right, then she needs to walk away on her own. It sounds like she likes drama - by putting you in the middle that is exactly what she is going to get. The card she holds right now is that your friend doesn't know about your fling.