Just found out that my girlfriend is pregnant. I'm not the father and want to be with her to raise the child as our own. At the moment she is thinking whether to end the relationship due to guilt for sleeping with someone else or stay and try put the past behind her. The father does not want to be involved in the child's life. I love her too much to let her go and I want what's best for the child. Please give me some advice on what I should do...

Were you two dating when she slept with someone else and if yes, have you dealt with it?
Being a parent is more than a notion and being one to a child that is not yours under these circumstances can be tougher than you think. Wanting her and being a father to this baby are two different things.
This is her decision to make.

Hi,

I think you should talk to her, tell her that you are willing to raise the child with her, even if he's not yours, even if you know that she (maybe) cheated on you. Tell her that you'll raise him as you own son. People can make mistakes, it's human.
You can go through that if you want it both.
(sorry for my english)

Until she makes up her mind, you can do nothing really but be a supportive friend. But I warn you that unless you can get over her having sex on the break and never speak of it again ever in life for any reason, then you need to walk.

Rejection, and a pregnancy is a helluva lot on ones mind, and requires patience, and NOT selfish fear. Her decision.

I'm wondering if you want to be a father to her child only to keep her close and in your life.

Be honest with yourself as to your intentions. The innocent child is destined to suffer depending how the adults in its life manage this unexpected situation.