since your husband has had another partner, he needs to follow up with proper testing at the proper times. he can get tested for gonorrhea, chlamydia, trich and ngu any time after 1 week post encounter. syphilis after 6 weeks. herpes, hiv and hepatitis after 3 months.
you also should be using condoms for sex until he's had all this testing done too. That won't help 100% for preventing std's but it's better than nothing.
are you sure that was a hsv1 igg and not a combined non-type specific herpes test?
grace
HSV-1 (cold sores) is carried by most adults, and you could have picked this up from a kiss from a relative at an early age or later on. If you haven't had genital symptoms then you can assume this is an oral infection since most infected with it orally do not have recurring symptoms.