that is the best pic of aiptasia that i have seen, sorry, but you are going to have to get rid of it. I get rid of mine easily with a Rid-Aip medicine, as well as 1 or 2 peppermint shrimp.
There is a nematod that is advertised to eat aiptasia, but the first combo is fine.
Get rid of it before those great polyps are irritated.
Do it in tank