Anyway, I'm pretty sure what we did was no risk.  But I'd like some peace of mind from you guys.  When I got there, we touched his unprotected penis with my hand for a few seconds.  Then put a condom on him.  I dry humped him with nothing except underwear on for probably 10 mins.  He was completely naked and had a condom on.  We rubbed our penises together, though he had a condom on, and I still had underwear between him and I.  At one point, I put back on thin sweat pants and continued dry humping, but the condom had fallen off.  There were two layers of clothing (my underwear and sweatpants) between our skin. We had a decent amount of skin-to-skin contact during this event, mostly legs/thighs/chest/abdomen.  But neither of us orgasmed, and there was no fluids exchanged.

Is there any chance that I could have caught any std from this event?  HIV/HSV/HVP/Sypilis?  Do I need to be tested before I continue to be intimate with my partner?

The encounter you describe did not put you at risk for STI.  While understand that your partner's excuses might be concerning, in our experience, most people tell the truth when asked.  More importantly however, thre is no risk from touching his unprotected penis with your hand (the skin of the hand is VERY resistant to infection) and dry humping, particularly if your underwear remained on, was also a no risk event.  STIs are not spread through clothing, even very thin clothing or clothing which gets wet with genital secretions.  

I see no reason for concern about the activities you describe and no need for testing of any sort.  EWH