Advice needed to take to next level

My wife and I have been together for almost 20 years and our sex life has continued to steadily decline over time. She is a beautiful amazing woman that just doesn't seem to enjoy sex with me. Never have we discussed her being with another man.

Over the past several years we have dabred with entering into a femdom relationship. As time has passed, she has assumed more and more control of our relationship. Two years ago for her birthday, I gave my orgasms to her. Since that time (other than me sneaking some masturbation) she has controlled when and how I cum. Our sex life has evolved to her masturbating me about once a week. She has me give her an orgasm once every three weeks or so after a length body massage.

On the occasions when she does allow me to enter her, after the massage, it starts with me stimulating her with my fingers or tongue until she is ready to orgasm. It ends with my "jumping on" at the last minute to ride her over the edge. More and more, she is cumming on my face and/or hand and only allowing me to enter her as she is coming down from her orgasm. Almost a sloppy seconds if you will. Over the past 2 years with her in control of my orgasms, sex has continued to decrease being replaced with an almost mechanical milking of me about once a week. I am to ask her to allow me to have an orgasm and she will decide if I do. There is no further discussion about it unless she initiates it.

This past week I asked her for some relief, she gave me the "maybe" answer. Maybe usually implies not likely but it could work out for you. I kissed her goodnight and rolled over to go to relax not realizing we would be taking it to another level in just a few minutes. About 5 minutes after her "maybe", she told me "get your lube". Taken of guard, I quickly grabbed the lube and squeezed some into her hand. She reached for my flaccid dick. She told me, I wasn't going to be able to satisfy anyone with my little thing, not even myself. I told her surely I couldn't satisfy her with it either to which she responded "no way". The more she stroked, the hard my dick became until finally it was standing at all it's 6 inches of so called glory. The following dialogue then followed while she continued my milking:

I asked "Is my dick still too small to satisfy you"
"Yes"
"Do you need a bigger cock"
"Yes"
"Do you need a bigger cock that will stretch you and fill you completely?"
"Yes"
"Do you need a great big cock that will stretch you and fill you completely?"
"Yes"
"After that big cock has stretched you and filled you completely, can I have sloppy seconds?"
Her final answer was "Yes" as came.

Any advice on how to take this forward?