I think the stories Mamma Roma told various people while 'streetwalking' were true. Those were the moments in the movie when we really got to know her; who she was, why she was that way, and why she did the things she did.
Here's my understanding of how her life unfolded: she was very young when her mother pushed her into marrying a much older man. She was about fourteen and he was, I believe she said, in his fifties or sixties. That would make him about forty plus years older than his bride. She said she couldn't take it after a while so she left him.
She also said the reason she walks the streets is because she chose to leave her husband. From what we learn later, she did not go straight from her husband to the streets. It seems she met another guy; who she may have loved, but he was not a good guy so he was soon arrested. With him she had Ettore.
On her own she struggled to care for herself and her child. She sent him to live in her village but she still couldn't manage to get her life together. By the time she met Carmine, a younger man, she was a broken woman. He cleaned her up and took care of her but then he became her pimp and put her to work on the streets.
Though he treated her badly, she made a lot of money for Carmine and managed to sock away some of it for herself. She sent for her son but all those years apart had taken its toll; both on him and on their relationship. She tried to make up for lost time but she went overboard. She gave him too much, treated him like a child, and expected too little of him. She interfered with his life and picked his friends; all while trying to shield him from the truth of her past.
The kid never had a chance but, then again, neither did she. Her mother raised her to value all the wrong things. Parents should nurture their children and raise them to be responsible human beings and upstanding citizens.
Woman, man! That's the way it should be Tarzan. [Tarzan and his mate]