I am a veteran strip-club widow.
I'd say the odds are very, very high that you've got an active cheater on your hands.
I cannot emphasize the following vehemently enough: DO NOT HAVE UNPROTECTED SEX WITH HIM.
Insist on STD testing. It will need to be repeated at intervals for up to 2 years (depending on doctor recommendations. Mine tests at 6 month intervals for 2 years, then repeats HIV testing annually. The latter he recommends for all patients). For that period, use a condom during sex---with the knowledge that any skin not covered may potentially infect you.
You need testing, too. Ask that this include a Pap to test for trichomoniasis. More importantly, because you are pregnant, it is CRITICAL that you be tested for Group B strep infection, even if your doctor did this test among the routine first-visit tests (as mine did). While this organism is completely benign to you, is the leading cause of neonatal pneumonia and infection-related mortality among newborns in the United States; it can be prevented with prophylactic antibiotics given before delivery. (Sometimes, the doctor prefers to deliver by c-section if the mother tests positive; this depends on how far before delivery the infection is identified.)
I can't emphasize this enough. I found out on the day I delivered my son that I was positive for Group B strep; the only reason I was tested is because my OB was on vacation, and the doc on call didn't have my records. He was weighing whether to allow me to try for VBAC or to do a section. Part of his assessment included the urine test for B-strep; the positive result tipped the scales to c-section, so that my baby would not be exposed to the organism while passing through the infected region.
YOU MUST BE TESTED FOR THIS SO YOUR BABY CAN BE PROTECTED. Even if your husband swears he did not have contact with any stripper or "massage therapist."
Why? Because your baby is too precious to gamble on the word of a man who's spending money his family needs in strip clubs and massage parlors--no matter WHAT he claims happened. Please, please, please. Talk to your doctor about this, and insist on testing.
I am so, so sorry you are in this position. I remember the bewilderment and hurt--and the financial aspect was a betrayal in and of itself.
Please know that this has NOTHING to do with you, or how often you had sex, or anything of the sort. It's far more likely to be related to intimacy issues--in him. Men who go to dark places to watch and/or be touched by women they don't know are often men who do not form real, mature connections with other people, particularly women. It's very confusing for the women in their lives--but has NOTHING to do with them.
I am very, very sorry for your pain. I hate that this time, which should be so special, has been so cruelly polluted. I understand how it feels.