My husband's child and my guilt

I got married 3 years ago. Her husband has a child from his first marriage (he divorced his wife on her initiative long before our meeting). The child lived with his grandmother, and now the husband said that we will take his son to us. I am absolutely against it - I do not want and will not be engaged in the upbringing of this child. My husband and I are actively building a career and there is simply no time for a child.

My husband at first agreed with me, but his mother (the boy now lives with her) began to cultivate in him a sense of guilt, they say, he is a bad father and a worthless man.

Their child was not welcome and the husband never dealt with them. I insisted that he should support the boy, and my mother-in-law, seeing this, decided that she could hang up on me as well. But I do not understand why I should do this while the mother of the child is alive and well, lives with another lover, does not deny herself anything. If she is not engaged in the child herself (and nobody touches her and does not blame her), then why do I owe everything to them and owe them something?

My husband was not interested in my son at all, and for years he did not remember about him. And now I was to blame for not allowing them to see me (although I do not mind at all, let him spend the weekend with the child). But I do not want to participate in it - it's not my child, not my problems and I do not want to take them on myself. I'd rather spend my time with friends in a fitness club better or groaning around shopping - this is my personal business and my choice.

I do not want to destroy the family, tk. otherwise everything is fine and my husband is a wonderful person. How should I behave? To date, I have voiced my clear position that I will not deal with the child under any pretext. A husband walks depressed, sighs sadly all day and raises a sense of guilt (well, in me at the same time). Mind he agrees with me, but this is his taciturn pressure that freaks me terribly. I feel that I am holding out of my last strength.