You know your H best and obviously you are thinking clearly. You mentioned you saw an attny so listening to legal counsel is best. That being said I thought I would just counter your points as sadly I do have some experience in this area.
My H tried to fight things. In fact, he backed out of signing our final agreement not once but twice just hours before it was due as per the judge in our case. All that resulted in was the judge getting rather pissed and my H's legal fees mounting (he was required to pay all my legal fees as per the settlement and they could not come from joint funds - told you I was not playing games, lol. The second time he backed out of the agreement at 5pm in the afternoon (the Agreement was to be filed at 9am the NEXT DAY) I essentially told my attny that I was not going to budge on my stance and I was fully prepared to go to trial and if we did go to trial it would not have been just my H and I in the courtroom. Once that info was passed to my H magically the signed agreement appeared.
Your H did not ask you if he could take out money to fund his affair so I am not sure (unless your legal counsel has advised you otherwise) why you would need to inform him of your withdrawal for a retainer. Plus, you should be asking him to pay all your legal fees anyhow IMO.
If you plan to retain your attny tomorrow then whatever he tries to do (kick you out of the house, stop paying bills) your attny should be able to get some immediate orders in place.
My take on things with my H was it was not my job to educate him on the law or give him any "heads up". If your H would like to be educated about divorce in your state he can retain his own counsel.
While my H was not w/a prostitute, just a "lady", I do understand the position you are in as I was in the same one. You and I are about the same age and my H and I don't have children either.
