(1) Early April; I made out, fingered, and received oral sex (to completion). I was careful not to touch myself after the fingering.

(2) Late April; I visited an erotic masseuse. I was completely naked; she wore an insanely small, lacy thong. During the massage, I fingered her *through* her panties, she licked my ear and neck, fingered my ass, and eventually gave me a "titty job." 

Encounter (1), I'm semi-confident that my partner does not have an STD, but I don't know for sure. Encounter (2)? Though of course safer, I'm very worried the masseuse has an STD... in fact, I emailed her after the fact (when guilt seeped in) and she said, basically, "that's none of your business. I don't know why you'd ask since we didn't do anything that would expose you." Not the answer I was hoping for.

I'm married with a child and though my marriage is "semi-sexless" it's just that; semi. Please let me know what risks I've brought into my house and what tests you think I need.

The only activity you describe with any risk for STI is receipt of oral sex.  Few STIs are spread by oral sex.  Unless your partner had an obvious sore on her lips, the only STI occasionally transmitted by oral sex is gonorrhea or non-gonococcal urethritis (NGU) and these problems typically cause symptoms of burning on urination or a penile discharge within a few days of exposure.  Personally, if I were you, I would not be worried at all.  Given your anxiety however, you may choose to be tested.  If so, the only testing I would pursue is a urine test for gonorrhea or chlamydia.  If this test was negative you can be confident you did not get an STI.  There is NO need for testing for HIV, syphilis, hepatitis, or other STIs.

I hope this information is helpful to you.  No one who you do not have sex with is at any risk for STI from your recent activities and any risk for sex partners is minuscule.  EWH

First, thanks so much for the reply. It's much appreciated.

Second, I have two follow-ups (but note, the second follow-up is loosely related to my original Q, so if I need to resubmit, I totally understand). Follow up #1: during encounter 2, I did touch myself after fingering the CSW through her panties. Being an able-enough reader, I take it from your reply that there was still NO risk from me doing that, but because I omitted it in the first post, I just wanted to be clear. Follow up #2: your post (and my situation) sparked a pretty frank discussion with my partner today, who is cautiously open to the idea of me engaging in rare, safe encounters like this every few months or so. Though neither of my April encounters involved this, would *performing* oral sex on a woman qualify as safe?

Again; if that's too far afield from my original Q, my apologies.

1.  You are correct,   STIs are just not transmitted from person to person by transfer of infectious material from person to person from one person to another on fingers and hands.  Thus the activities you describe are not risk.

2,  congratulations to you for discussing this topic with your regular partner.  I'm sure that the conversation was not easy but it is best to be forward and forthright.  Masturbation whether done by yourself or someone else is safe sex, as, for all practical purposes, condom protected sex when condoms remain intact and are worn throughout sex.  Your question however related to the relative safety of different forms of UNPROTECTED sex.  In this area the risk for acquisition on bacterial STIs varies according to sites of exposure.  If a partner is infected, the greatest risks for acquisition occur with rectal intercourse (risk is greater for receptive rectal intercourse than for insertive rectal intercourse).  Penile vaginal sex with an infected partner is next in terms of risk with male to female risk of transmission being greater than risk from female to male transmission.  Finally, oral sex represents the lowest risk activity for bacterial STI transmission/acquisition.with risk for men being small for acquisition of infection and risk of acquiring pharyngeal gonorrhea from performing cunnilingus on an infected partner being lower still.

Finally, as you consider occasional interactions with others beyond your current relationship, I would be remiss if I did not also remind you to the risk for acquiring bacterial STIs is summarized above, there is also a very small risk of acquiring herpes viruses through unprotected exposures as well if you do not have HSV infection already. Further comment on this topic is well beyond the scope of this reply but I did think it important to mention.

I hope this comment is helpful.  EWH