All perfect praise be to Allah, The Lord of the worlds. I testify that there is none worthy of worship except Allah and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.
There is no harm for the man to sleep with his wife on the same bed while she is wearing silk as it is lawful for women to wear silk, as we have previously underlined in fatwa 326137. It is impermissible for the Muslim man to wear silk, but he is not forbidden from sleeping with his wife while she is wearing it.
As for using the silk fabric as such, the Shaafi‘i book Hawaashi Ash-Shirwaani ‘alaa Tuhfat Al-Muhtaaj, with regards to the use of silk, reads, "Likewise is the silk bed napkin; it is permissible for the woman to use it even for wiping the man's genitals, and it is prohibited for the man to use it even for wiping the woman's genitals." Hence, there is no harm in doing what is mentioned in the question.
Allah knows best.