No you are not wrong thinking she is running away from dealing with this, if her son is to her husband that passed away then she has replaced him with her son and she believes that he is her only connection to her husband now that he is gone and she doesn't want to lose that but in the process she is making her personal life unhappy because she doesn't know how to have a happy medium and even things out. She has made her son her life because she is the only living parent now to care for him but what she doesn't realize is that her son is an adult and she is stopping his growing process by babying him and treating him as if he is still a child. As far as your relationship goes she has to realize that she has to have a life of her own and that having that type of relationship with her son is not healthy. People that have children are very concerned and choosy about their dating options. They often avoid going out and seeing someone, and even if they do they hesitate to bring up the topic of their children. Dating in such circumstances are not easy for both partners because they start hiding things from each other which only creates distances.
Children no matter what their age sometimes complicate things. Deciding when to meet your partner's children is a very crucial decision in dating. First try to extract some information about their previous relationship and their children's habits; likes and dislikes. If you really love someone, you will have to compromise on a lot of things and children might be just one of those things even if the child is an adult because they are protective of their parents and usually will find something wrong with the person their parent is dating just to have their parent to themselves. It's this way of selfish thinking that usually ends a relationship faster than it started. In order to have a long term relationship it's important that you form a relationship with her you have to have a relationship with her son as well.You are going to have to show him that you have his mother's best interest at heart and that he has nothing to worry about but in order to do that you have to get the okay from her to do so and it seems to be a touchy subject with her and so you have to find out why it is that she shy's away when you mention her son the sooner you can find out why that is the sooner you can form a relationship with the son.
She will have to let her son know about your relationship sooner or later. She is living in the memory of her husband and may feel guilty for dating, like she is having an affair on him and she may think her son will not accept it because of his father but she has to realize that her time of parenting is done he is an adult and should have his own life and her as well. The sooner she allows her son to grow the happier she will be and the fact that she lost her husband through death does not mean her own death sentence, life goes on and I'm sure her husband wouldn't want her to live life alone without someone to love in it. She may need some counseling to help her get past losing her husband and allow her son to final grow up and have some responsibilities, I would suggest you give her some more time before talking to her about meeting the son again. He might have already said he will not accept anyone she dates it's a territorial thing because he thinks he is now the man of the house and has been since his father died.