Helping my uncle's wife

My aunt is younger than my uncle, he's 52 and she's 34. He is also a drunken overweight loudmouth who shows his wife little respect. He married her to start his own family and hasn't had any luck. Of course, it's all her fault and the lazy do-nothing uncle of mine isn't anyway responsible. But thanks to my mother and sister who helped my aunt checked over and she was found completely healthy. No chance getting my uncle to get checked over, my mother was very annoyed at the actions of her younger brother but said nothing as it would make it worse for her sister-in-law. My mother isn't so easily put off and decided she should help get her sister-in-law pregnant. To that end I was asked to provide semen to get my aunt pregnant. I was shocked at the request, mainly because it came from my mother. But I agreed and provided several samples, but to no avail. Finally late last year we were at the family lake house and my uncle was drunk as per usual. My mother asked to provide semen for my aunt, as my father and sister were away for several hours I agreed. Uncle was passed out from the night before, where he had drunk himself unconscious. But this time I was to deliver it straight into my aunt, fucking my aunt was a bit of a shock. But not much more than masturbating into a cup for her, so we had sex ion my mother's bed while she stayed outside keeping watch. I really enjoyed fucking my aunt and told her so. Over the following week we were there, my mother had me fuck my aunt. Anywhere we could go without getting caught with her on watch. But we did get caught dressing after the act, by my sister. Who willing agreed to keep the secret and also help keeping watch. Only people not in the loop were my father and my uncle, my father was far too straight lace for such a thing and my uncle wasn't the type to take it well at all. Back home living next door to my uncle/aunt, my mother kept an eye on developments as they say. Also testing my aunt regularly, finally getting a positive test than another. My uncle was excited and got drunk as per usual for him, tests followed no health problems were found. Then my uncle decided suddenly he couldn't remember bedding his wife around the time the baby was supposedly made. My mother told him the number of weeks pregnant isn't an exact science and that's why they can't give the exact day the baby will be born. But she knew would do something stupid, like getting a DNA test. So, she said she would arrange the testing and he won't be involved except for a sample. He trusted his sister as she was the only one still cared for him (his words). He provided a sample, and my mother got the DNA test done and the test said he was the father no doubt at all. He was now satisfied and acted like a jerk as per usual. Only one detail he didn't know was the sample tested as the possible father's sample was mine. My aunt didn't know the test had been done until later as she would show it on her face due to worrying about it. Only me, my mother aunt and sister know I'm the actual father. So, at the age 25 and in my last year of university I'm to be a father. One thing did chance with my uncle he isn't as watchful on his wife anymore, I have taken advantage of his lack of interest in her whereabouts and have asked her for sex several times. Being a nice aunt, she has agreed, after all she is carrying my baby. This isn't known by my mother or sister. Uncle isn't at all well at the moment, but should get better soon if he follows doctor's orders and cuts does on his drinking.