I'm sorry this is happening. And I am not too optimistic about your chances.
Start by talking to the owners of the livecam site and tell them you want your recordings taken down. Threaten to sue (they are your images and you are readily identifiable in them, yes?) if you do not get cooperation. Engage the services of an attorney if you must.
As for where the videos have been shared, yeah, you'll probably have to contact them directly and try to do the same thing. And yeah, this is going to be difficult, time-consuming and expensive. And it may not even be that effective, as you are dealing with international law, porn, and website owners who may just call your bluff if you threaten to sue. Plus you have no idea how many people (maybe none, maybe a million) have right-clicked and downloaded your videos, or have stopped them frame by frame and taken screenshots or even photographed their own computer screens with your content on them.
And now you know why that was a really, really stupid thing to do. I do hope the boys and girls at home are reading this.
This is why you don't make sex tapes. This is why you are careful with what you put online.
Because - surprise, surprise!
- you may impact your future in an incredibly negative way.