Wow, Kendyll,
That kind of situation would be very hard for me to handle. It is a rare look (for me) at the side of the partner of someone with DID. No wonder my spouse has trouble with me being split - not that we EVER can openly share who we are with him (he's got limits in acceptance).
Do you have a T? I forget. Sounds like you need someone to help you think and bounce ideas and stuff around and someone to help you. I too would have huge problems being "used" in any way for several people's sexual gratifiication. It is a tough situation to work in, imho!!!
You must take care of yourself as well as any of them. You can't just completely "give yourself away" to them if it is violating you in some way.
Be kind to yourself
Leslie/Pixies