mirena IUD strings

Hey guys! I just got my mirena inserted today!! It didn't hurt one bit besides for the 1 second with the sound and the second it took for mirena to go in... I wanted to know if my boyfriend fingering me would potentially make mirena come out, I don't want him to pull on the strings, also, does using a tampon affect the mirena strings??? My last question is how exactly does mirena "attach" to the uterus and stay in there??