The Problems with marrying a Rich Guy

I was lucky I caught the eye of someone rich and we married after 2 years. Problems started within month of our marriage, His over drinking and doing drugs, as well as smoking and chasing other women. I was lucky again, as I was acceptable to his family and was fairly safe from divorce. The other women were not acceptable and were referred to as little better than bar sweepings. My one problem I had to overcome was getting pregnant and after 2 years nothing. My husband done his duty once a month and it not worth describing, more often than not falling asleep on top of me. With my in-laws wanting grandchildren, pressure started to mount and so I collected a sample of his sperm, I had the sample tested and the result was woeful. I had 2 choices, IVF and get someone else to do his duty for him. He did have a younger brother, who he teased regularly as a nerd, geek, wimp and reject from life. His brother doesn't drink, smoke or do drugs like my husband and didn't date at all. I was lucky to get along with the brother and accompanied him to important events, like his graduation and graduation ball. My husband didn't mind and was usually busy with his personal interest's drugs, smoking, drinking and loose women.
I was thinking of what I could do get pregnant, my brother-in-law came to mind. I knew he was a virgin and not gay as my husband sometimes inferred. I always saw him checking out women, never men and caught him checking me out a few times also. As I got on very well with him and knew I could trust him, I thought I would ask him. It was difficult knowing how to ask him and then he asked me to help with a personal problem. It wasn't him asking me for sex but help in finding a woman to take his virginity. He said he would've asked his brother, but he knew he would only get teased instead. I knew this was my best chance and told him of my problem with getting pregnant and the reason why. He was shocked especially when I offered to take his virginity in return for him getting me pregnant. But I also asked him to keep it secret and just between us and he agreed to keep it secret. He said he had to think it over, it didn't look good that he would agree. But thanks to my husband he did agree, my husband being annoyance he is to his brother. Teased him as was fairly usual for my husband, when his brother was around. So, my brother-in-law agreed, the next time husband was away. We started and I taught him to fuck me, we took no precautions. After several month of no results, I started wondering if both brothers couldn't father a child. But I then missed a period and then another, I got check and I was pregnant. That was 7 years ago, I now have 3 beautiful children and all fathered by my brother-in-law. He hasn't found a woman for himself and only fucks me; my husband has no idea of who father of the children are really. He takes it for granted it's him, he has slowed down on his partying to health concerns. But still drinks and does drugs at home, he thinks he is fucking me still. But he isn't as he is usually passed out and I just sleep naked with him, he thinks we have had sex. If I want sex, I see his brother.