Cucked on birthday weekend pt1 [cuckolds perspective]

There has been a change recently in my Mistress. She is starting to really come into her own. This is both a blessing and a curse as now she is starting to take the lead so for this year on my birthday so was going to indulge some of my fantasties. Thats why a few days before the weekend started she gave me a ruined orgasm and afterwards told me to put my cage on. It's one that I can plug in to e-stim but she told me I wasnt allowed until she told me to. Friday night we went out to the local beerfest. She told me that she was going to fuck someone this weekend and that I was to search and find someone.I had a look-see if anyone was about on Fab throughout the night but we couldn't find a match so at the end of the night we called it a night and went home. She still insisted I carry on searching and eventually we settled on one guy who was free that evening. Not quite our type but tbh pickings were quite dire so we agreed to meet that evening. Mistress had already me order her a new lingerie set which had arrived that day and she made sure that I helped her get dressed and prepared for another man before I too had to get ready in my sissy clothes. I packed a holdall with a blanket, some extra e-stim toys, my mask and restraints. Shortly after we got ready we received a message on fab that he had arrived. A few last minute preparations and we were out the door and getting into a strangers van. The man who would start off the birthday proceedings by fucking my Mistress in front of me…….