I don't think I'd ever want to be a part of a threesome where not everyone was there because they genuinely wanted to be (in whatever capacity that happened to be). No one should have to be there as the prop body parts to fulfil someone elses' fantasy. I've been there once and although I wasn't the "prop" it didn't sit with me well after the experience that one person had basically been used just to make things happen.
Sorry to continue with the hijack!
Everything will be ok in the end. If it's not ok it's not the end.