Thanks for posting your query at DoctorSpring. I can understand your concern.
Hpv would require skin to skin contact to transmit. Since you were wearing lace underpants there seems to be a less chance, however there could be a small chance of transmission.
I would recommend that you request your boyfriend to get his genital warts treated and to use a condom during sexual activity till the lesions are treated.
In case you see any visible lesions, it would be advisable to seek treatment.
Genital warts can be treated, do not worry, as I mentioned the chances are less, but please be careful henceforth.
Hope I have answered your query. If you have any follow-up queries, please feel free to ask as follow-up.