Forced to watch a threesome with my former gf

First of all , sorry if my English is not so good. I’m living in a not english native country and we’re learning english only at the school.

This story happened a few years ago at New year. My gf at this time (2 years younger then me) and I were invited to a new year party at the house of a former friend (1 year younger than me) of me.

About us: I’m about 5.8 ft, short hair, normal looking. My former gf, let’s call her Kerstin. She was about 5.1 ft, long blond hairs, 80B breasts .
My former friend is like me about 5.8 ft, but long hair like it was modern for former days and more the typ of a bad ass surfer boy. Let’s call him Jeff.

The celebration itself was nothing special, only a few people I knew from him. We drunk, talked and had fun waiting for midnight. Then kerstin and I got horny and wanted to fuck. We went to Jeff’s bedroom where we got naked and I sat down on his bed while kerstin went on her knees and start sucking my cock. My cock is nothing special, little bit over the average but very thin for this large. Then the door opened and Jeff and his gf walked in.