You should probably stay away from them and meat cleavers.
I agree with you slasher...
but for a reason... your best friend returned back to you because of jealousy, to my point of view. She hates to see you around with another girl after you were her's. Sometimes it is too simple to see it.
I don't see this situation the way you do! I agree with the simple part.
You are calling yourself a cheat and a jerk. Why not call yourself a loser too? Even if you have been called something in the past by someone, why wear it? Is that what you want?
I would think if you think like you are something then you will act it out, over and over again all your life.
It is your choice, if you want to be a one girl guy or not. Some couples agree or at least communicate in some manner that is what they want. Others can agree that they want casual relationships with others and that is acceptable for them as long as they want that lifestyle.
The bottom line is you have to determine what is right for you and then make it a value. Life will always have its twists and turns though so be aware that anything can happen.
No one can tell you what you should do or how you should treat your girl, after all, she is part of you.