When my first wife Helen was 8 months pregnant, I came home early and found her on our bed naked with her 'best friend' Miranda....She was caressing Helen's very swollen belly with babyoil, and sucking on her engorged and full 36d breasts......Needless to say, I got an almost instant erection, and quickly stripped off! Miranda saw me and gasped, and Helen looked shocked.....I just moved behind Miranda as she was astride my wife, and I slid my cock into her from behind....it was a surreal moment, and nothing was said at the time, but my god it was amazing!