Disclosing advice

I (31f) am seeing a guy (36m). Weve been going on dates about once a week that have been going really well. Weve been on about 6 dates. On our last date we had sex for the first time. We had only kissed prior. I have been thinking today that I have gotten cold sores in the past and didnt disclose that prior to kissing etc. i feel like i am gonna drop that bomb on him now and sound like an ass. Any advice?