My parents didn't know about my relationship until it was serious. Like you, I don't just introduce anybody to my parents. They have high standards and I trust their standards - therefore, if the guy I'm dating isn't up to their standards, there's no point having the family get to know him because he won't be around long.
Your situation sounds like it is entirely the mother being overbearing and babying her son. If your boyfriend genuinely wants to meet your parents, he should be telling you, not his mother, and then together you can decide when the time is right. If you don't stand up to the mother and put her in her place (politely, but firmly stating that this is your relationship and your boyfriend's relationship, not hers), you could face a lifetime of her trying to push you around and run yours and her son's lives. This could ultimately end your relationship if you feel that there is a third party involved, especially one that treats you like you don't matter. She has no right to speak to you like that. You are not her daughter. Furthermore, when you tell your father about the relationship, there is no need to lie about how long you've been together - you can say that you've been together for x amount of time and didn't want to introduce him to your boyfriend if it wasn't going to last.