It looks like your boyfriend has become one of the kids and you’ve become the nanny. His mom has resumed her position in his life and is doing all she can to evict you from the picture. He likes things as they are because the two women in his life are taking care of all his home and parenting responsibilities. The dinner situation would be the last straw for most people. They sit down for a meal and you’re left eating a sandwich alone in your room? It’s a sad picture of your place in this family in spite of all you do. I can’t help but wonder what the kids make of it.
You seem very committed to the children. His mother certainly can’t do for them what you are doing. He doesn’t seem inclined to. I’m concerned that your worry about the children’s welfare is really the glue that is keeping you in this situation, not love between you and your “boyfriend.” If your relationship is primarily with the kids at this point, you could move out but still stay in touch. Better to be a loving “auntie” in their lives than an unwilling servant.
You have some hard decisions to make. Your boyfriend isn’t willing to change. He’d rather be a boy in the house than an adult partner for you. Are you willing to continue being the unpaid nanny? Do you love these children so much that you can’t bear to leave them to be neglected by their father and grandmother? Are you willing to sacrifice any chance of having a genuine partner and children of your own? Please think hard about these questions. If you don’t take care of yourself, you could easily slip into continuing this arrangement for years. You would end up resentful and lonely. The kids would end up with a very, very bad model of the role of a woman in a relationship. And your boyfriend would never grow up.
In the meantime, you are within your rights to let the school know about the situation. The teachers expect you to take care of things because you always have. If you continue to act as a buffer between the school and the father, the school will never see him as the responsible party and neither will he. Please tell them to treat your boyfriend, not you, as the parent. If you get out of the middle, the school will push him to take care of his children. If he doesn’t and there are serious consequences, schools are mandated to report neglect.
After 6 years together, this all must be very disappointing. You miss the relationship you had for the first 4 years. But that’s not what your boyfriend is offering you now. I hope you have some good friends to support you as you figure out what you want to do next. If not, please consider seeing a therapist to get some support and perhaps some practical advice.
I wish you well.