You have a big decision to make
You have to decide what's important to you. Your sexual fulfillment or your stability and marriage. The likelihood, in this case, of keeping both may be slim.
If you are completely dissatisfied with your sex life and you want to pursue your fantasies, then it seems like you're going to have to have an affair. You're going to have to find your information about what you want, you're going to have to assess your needs and then you're going to have to find yourself a dominant and begin your affair. If you plan for the affair to be long term and to eveolve into a potentail relationship, then you will very liely be found out. Most affairs are. Something about the cheating partner just "feels wrong" to the other partner, if he pays any attention to you at all.
However, if you feel your sex life is not worth wasting your marriage over, then you need to unsubscribe from forums like this and resolve yourself to the fact that your sexuality for the forseeable future will consist of your servicing your husband, having him manipulate you and you masturbating.
The only other option you have is to come clean to him. Tell him of your desires and of what you are considering. If you are considering having an affair to find out what you want, then tell him that, too. Be completely honest. He might get irate, he might be hurt, but then again, he might understand and give you permission to seek out your fantasies.
You must choose your own course. However, if you have further questions, please ask. Don't try to do this blindly.
You're not "allowed" to masturbate?
I think your notes contained the following information; please tell me if I'm wrong:
He cheated when you were working 70 hrs a week and
he has an illness that reduces (at least) your ability to have sex with him and
you have (reasonable) scruples about cheating on him and
he is unwilling to participate in those physically sexual activities he could with you and
he has online relationships with sexual content and
he wont _*let you masturbate*_?
The behavior you describe sounds abusive to me. Sounds like you have a bdsm relationship where he has all the power and (despite his illness) sexual outlet while you have the limitations but not the features you'd like. Your interest in bdsm is the least of the problems you mentioned.
At the risk of sounding like Dear Abby, have you thought about counseling? With him if possible, but (having been there myself - with my wife) you might want someone to talk to in real life. Find someone who does relationship / marriage / couples counseling and tell your tale. A professional wont be shocked and might be able to help.
You have my very best wishes.
At the risk of sounding unsensitive. Forgive for what I am gong to say
Why dont you slip some viagra into his food and when he get's a woody for the next 4 hours walk away. Disconect the internet Then have a little talk with him. Tell him of your needs. That he is being a selfish jerk. It is hard to argue when you have a rock hard boner and cant do any thing about it.
I think he will come around to your thinking.