Friend gives me vid proof of my ex fucking him

years ago, i think it may have been done on purpose although im not totally sure, my friend lent me a video that had something interesting on it...it was a blank vhs tape that had a bunch of random stuff on it but i got to one point and it gave me proof that i needed. i had assumed that my ex that i had recently broken up was sleeping with my best friend....well now i knew, because there on the screen in his bedroom was my ex under his blankets in his room. she was acting all shy in front of the camera and he kept asking her to move the blanket but she wouldn't..he finally pulled the blanket off her. she squealed and laughed as the blanket disappeared and on camera was my ex in only a bra and panties. he came closer to her and the camera went a little wonky for a few secs and she continued to giggle...the camera then pulled back and she had no bra on but was covering her breasts. he then set the camera down facing her and he began kissing her...he moved down and sucked her breasts for a minute or so. he then grabbed her panties and pulled them off...she put up no fight. he kissed her some more and then slid down and i could barely believe what i was seeing.....it was a little hidden from view but you could tell he was licking her pussy. i felt so hot..literally...a little angry and betrayed but a lot turned on..... i pulled off my pants and started playing with myself......he had always flirted with her and she flirted back...it always gave me a bit of anxiety and i didn't like it but somehow now it had changed into arousal. he started fucking her and i was leaving my body with excitement.......he fucked her about 5 minutes or so and then all of a sudden static and then some thing else random was on the tape.......i watched it over and over again....wish i still had it..it was the early 90's so no digital technology and i had no way of copying the tape.....i watched it enough to ingrain it into my memory and reluctantly gave it back to him...didn't know how to talk about it, so i just gave it back and never said anything as i wasn't sure if he know it was on that tape or not ...knowing him he may well have known and he wanted me to see it.....her friend i learned later was really worried during this time because they were fucking all the time and not using condoms..she was worried she would get pregnant. my best friend that fucked her is the same guy i talk about in my threesome story which happened later. as i said he was always hitting on my girlfriends especially when he was drunk. to his credit he did offer his girlfriend to me once when he was really drubk but it was in front of my gf and his gf and we nervously laughed it off...too bad we were shy...would have been hot to swap and fuck each other's girls in front of each other....he kept asking me to use a vibrator on his gf.......i was a little protective of my gf at teh time so i think he pushed him away....my gf at teh time was my gf who he later fucked in that threesome story. his gf was till his at that time too but she was out of the loop and not aware that we were having a threesome....ah youth!.....now i only dream of such debauchery!