Girlfriend Dilemma

My girlfriend recently split up with me, with the reason that her friend was worried i cannot control myself and made her choose between me or her friend.

I know in myself i can control my anger issues and i know that if she gave me the chance she would see it too, but i don't know how to approach this problem.

I have never hit or abused her verbally, i never would, my anger stems from physical abuse as a child and i have learnt to stop running from it, which is what was my control problem in the first place, i was scared so i couldn't control it, but now i can and i don't know how to show her.

Do i need to prove myself to her friend?

This isn't the first time we had split up either, we had split up just before christmas after spending just under 1 and a half years together, and after new years, i went out got drunk and slept with another women, all i craved was the affection i got from my ex girlfriend at the time but she had made it clear that she didnt want me.

Then all of a sudden about a month ago, she turned it around and said that she wanted me back and how much of a mistake she had made, and told me that she still loved me, so we got back together. However she found out about the other girl, and accused me of cheating on her, i don't understand how it was cheating when we weren't going out and she had made it clear at the time that i wasn't wanted.

I really love this girl and she is the only girl i have ever wanted to spend my life with, but now it seems that she is just throwing it away, because her friend has convinced her that i'm no good for her.

I honestly thought everything was getting back on track, her friedn gave her this ultimatum, me or her, and i know that she values this friend as family, but shouldn't i have matter aswell?

She says it's too hard for us to get back together, as i have let her down in the past, but since we got back together a month ago things had got better and she even admitted things had got better, and now i'm alot better in myself, because i no longer lack the connfidence in myself to deal with issues.

I have made it clear to her i want to be with her, to be there for her, to be an emotional to her, to be a shoulder to cry on, and still she is putting her friend first, it is driving me insane, and many of my friends say i am crazy to be putting up with this and still wanting to get back together with her.

I really want her back but her friend is standing in the way of us, what can i do?