Help me from having to surrender my dog!

My name is Angie.  I have a 7 year old German Shepard mix that I have had since she was 5 weeks old.  She was found in a trash can with 5 brothers and sisters.  Through the years she has had some aggressive behavior issues.  Recently these behaviors have gotten worse.  I have been a single mom for most of my life and my dog Maggie has always been very over protective of me.  To the point where I can not have people at the house with out muzzling her. I love this dog with all of my heart. She is super smart, sit, stay, shake, roll over, high five, etc. She has helped me through a lot emotionally. I am not so sure I can afford boarding and train (and I know that is what she needs) but, I wanted to reach out and see if anyone can help us. I hate to beg people for money but,  I am forced with possibly making the decision to surrender her.  I am not willing to to surrender to a shelter so I have been trying to explore options of rescues but I am hoping that with training I can keep her. This is one of the most heart breaking decisions that I have ever had to make.  

I will say this, if I am not able to make my goal I will give everyone their money back.  I need to get her into board and train as soon as possible.