<human>: Hey Reddit, I'm trying my best to help my brother in this awful situation, so any advice would be very appreciated!

My brother has been with his fiance for a couple of years and everything seemed great between them. He has worked hard to help support her financially through nursing school in the past few years. They had an unplanned pregnancy during their engagement but were very happy and excited about it. She graduated nursing school in June and shortly after gave birth to their son. She found a job in July and things seemed to be working out for them.

About one week after starting her new job, my brother came home from a long day of work and both his fiance and newborn son were gone. Her family had helped move her out while he was working. He was completely shocked and later found out that she has been talking with someone else for almost a year, and planned to leave my brother for this other guy.

She has cut off all contact with my brother and is refusing to let him or his two other sons (from a previous relationship) see the child. She is apparently creating lies that my brother is unfit to help take care of his newborn son. However, I know for a fact that my brother is a great father and works very hard to support his sons. My brother is in a poor financial situation right now, especially now having to pay for an apartment and bills he can hardly afford on his own. 

My brother wants to fight for custody of his son but cannot afford an attorney or even afford filing on his own. He isn't wanting to fight for full custody because he believes that the mother should still be in his son's life. So far my brother has created a gofundme page and is sharing it on facebook. If anyone has any other advice, please let me know. I really hate to see him in this situation, he's devastated.

Could you distill the essence of the text into 1-3 sentences?
<bot>: Brother's fiance leaves him unexpectedly, takes newborn son with her, cuts off contact and is refusing to let him see his son. Brother is in very poor financial situation. Need advice!