When The Sister Grows Up Way Better Looking

I had a long time girlfriend from 19-27 or so, when we met her brother was 17 and her sister was about 8, she was always very good SIL, we spent a lot of time having all kind of things, basically she was just like my sister too…
We went to live to another state around 23 so her sister eventually started to visit us about once a year. By the time we were about 25 she was full teen and grew impressively, she was very tall and went full blonde model, she has a spectacular body, I really didn’t put much attention because I loved her like my sister, I saw her grow…

The day I actually realized how hot she was I was coming from shopping and my SIL was hanging out with some neighbors were we lived in… I was parking and saw this tall very curvy girl and I immediately thought “wow, that girl is hot!” And seconds later I actually recognized her, it was a shock, she was in jeans and looked way way better than my GF, not that my GF was not hot, but the SIL just was on another level, she had a perfect butt, had also big boobs but also was way taller, had much prettier legs and just the classic latin hour glass shape… it was just a few months before I broke with that GF, but every time we had sex in those final months I came with her sister in my mind, I was not really fucking my GF anymore