Marriage Failed

I'll call myself Jane 31 married at 26 and no children, my ex husband I'll Larry 32 couldn't commit to having a family and wanted to party instead. I moved back to my home state and stayed with my brother I'll call Mark 31, yes my only sibling is my twin. Anyway Mark and me are polar opposites, I always liked to enjoy myself, Mark didn't he preferred to study and so ended up with a great career. Feeling low and dejected, I was hanging around Mark's home all the time. Even those he wasn't a party person I was a downer to his lifestyle. That all changed, when Mark was hit by a baseball in his groin. The neighbors children were playing and one hit the ball just as Mark left his house. I thought it was funny at first, but seeing the pain and other problems Mark was having. I called ambulance and he was taken to hospital, he had to have surgery to repair damage done and the doctors said he was lucky. It could've been fatal, on him getting back home a couple of weeks later. I was going to be his fulltime nursemaid, till he was up and about. I had to sponge bath him and at once got a shock on how big his penis was. At first I thought it the swelling from the accident and surgery. But it wasn't, it was his normal size as all the swelling had gone down before he was allowed home. He was as big as Larry was with a hard-on and Mark was just on the slack. But I took good care of Mark, but had to masturbate afterwards sometimes. The final week before he would be up and about and looking after himself. I decided to join him in the shower, he was stiff and had restricted movement in groin area. So I gave his body and sponging and myself as well. Mark got aroused by my being naked in the shower with him and got a hard-on and was a little ashamed by him getting a hard-on. I on the other hand got aroused on seeing his full length cock poking at me. I tried to ignore it, but I couldn't and while sponging it I had to play with it. Which ended in me getting fucked by Mark in the shower, mainly due to me wanting him to fuck me. After the shower, all taboos had disappeared and full on sex was now in full swing. I fucked him in his bed after the shower and spent the night with him as well. Only late the next day it dawned on me I wasn't protected, why would I be. I wasn't dating and therefore not fucking anyone. Except I had just fucked my brother 4 times. I thought what are the chances and dismiss the thought, which was pretty stupid thing to do. Nothing at all, I had tried to get pregnant while married by not taking precautions and didn't get pregnant and so thought I was okay. But we did start taking precautions from then on, but it was too little too late. I got pregnant and so our mother I'll Lucy 48 widow came to live with us. As every test there is show the baby was healthy, I'm due next month and having a boy we're calling Robert after our late father. Lucy wasn't happy of our actions at first, but was looking forward to being a grandmother and on her last birthday we had a threesome and she now services Mark as well.