Holiday with my Sister

I'm Egar 28 single, I work in I T development. I own my own home and I'm paid very well. I'm not a party guy, I keep to my self and work. My sister Robyn 30 divorced 2 children and lives in an apartment 3 miles from me. It started last year, my niece 7 and nephew 5 were on holiday staying with their Father for the holidays. Robyn had to take her holidays from her work, but couldn't afford to go anywhere. I also was going on holiday and hadn't made any plan to do anything. My Mother suggested that I go away for my holidays, but I wasn't keen on this. I keep it simple I told her and stay where I'm comfortable at home. Then my Mother talked to Robyn and suggested that if she wanted a holiday away, that she should help convince to go somewhere for a holiday and that she could go with me to help me feel secure. Robyn thinks I'm a NERD and boring, she has told me so. I'm a bit like a cross between Raj & Sheldon in Big Bang Theory, quiet and shy around people like Raj around women before he started drinking and a know all like Sheldon. But a free holiday was something that was too much to miss for Robyn. So I was convinced to go by them and Robyn made all the arrangements. But being late in the bookings, she could only get 1 room at the resort she had picked out. Well shared a room for years as children and so she took it. Only thing was on arrival we found the only had 1 Kingsize bed in it. I just followed Robyn around at the resort and paid for everything she wanted us to do. She rented a car and we went around looking at the sites.
5 days in to our 10 day stay there was a big party at the resort and Robyn had a bit too much to drink. I don't drink and I took her back to our room just after midnight and put her to bed. I went to sleep, at 2 am by the bedside clock I was awoken by Robyn in the bathroom and she was not well. I got up and helped her clean herself and then changed into her PJ's and we when back to bed. I was just starting to go back to sleep. when Robyn asked me Are you asleep yet and gave a shake. I asked What's wrong. She said I'm Horny now, I need a fuck. What's that got to do with me I asked, she your a man and I need your cock in me. I'm your Brother I said and she said So what I'm on the pill and this might be the only chance you get to fuck a woman. Don't waste it. I replied I'm not sure what to do. Don't worry I will show you She said and then she grabbed my cock and was soon sucking it. I got hard and she got on top of me and started moving up and down on my cock. After I came she sat on my face and told me what to do. Then we went back to sleep, I woke first and went for a shower and she came in and joined me in it and then went down on me again. We had sex in the shower and after went down for a late breakfast. That night she asked me to have sex with again and we did it everynight till we left for home. 2 Months later Robyn came over and told me that she was pregnant to me and our beliefs won't left her abort it. She told the rest of the family that had a fling at the resort and got pregnant and can't remember what was he name. So our Mother suggested that Robyn and her children move in with me. Which she did and we had sex once a week and on the weekends the children were at their Fathers place. The baby is due soon and I must say I'm looking forward to being a Dad.