I am not sure if this has been addressed, but I wanted to post it in case it helps someone who is going through this kind of infidelity and their circumstances are similar to mine.
My D day was five years into my marriage when a stripper/prostitute called me to tell me she was having an affair with my husband. My ex admitted it, and said she was the only one. Also, she was apparently blackmailing him! I was mortified and I made him leave the house. Went through his cell phone bills and sure enough, there were other strippers. He was carrying on with two to three strippers at any given time.
I went through all the records that he had handled and also discovered significant financial infidelity. Suffice it say, I knew that I did not want to stay in the marriage, even though he was acting remorseful and wanted to R. I was done. I was in survival mode at this point.
I also knew he couldn't have gone from the nice, decent guy he'd pretended to be to a lying, thieving, out-of-control sex addict overnight and I strongly suspected he'd brought his problem with him into the marriage and he had covered his tracks extremely well - until D day.
I then called his ex wife and asked her why they got divorced. She told me he had cheated on her over and over. He had told me that she was the cheater. I'd taken his word for it. My bad. I paid dearly for that.
Next day I saw an attorney and was told that since I had made significantly more money during our marriage than he did, I was looking at having to pay him alimony and give him part of my 401K in a divorce. We live in a no-fault state. Doesn't matter what he did. I decided to go a different route.
I filed for a legal annulment, based on fraud, and stated I never would have dated him, let alone married him had I known he had a history of sex addiction and serial cheating and that he'd lied to me about the reason for his first divorce. That was the fraud. The judge agreed that I had been defrauded and he granted a legal annulment. They hand out two to three legal annulments in my state each year, per my attorney.
I did not have to pay my ex anything and I kept my 401K. I at least was able to start over again and make a happy life for myself, free from the financial burden of paying him alimony and sharing my retirement savings.
My guess is that most people do not even know that this option is available, or they mistakenly think that annulments are only for very short-tern marriages. Laws on annulments vary by state, but if your situation is similar to mine, and you want out, talk to your lawyer. In my state, it is required that you do not live as a married couple after you discover the fraud. Another good reason to boot them out of the house on D day.