Defamation from previous employer

Hi all,

Have recently left my previous employer for a close competitor (EU equity research, director level). Few weeks after I hear from three different ex colleagues that employees of the bank (quite senior) have made up a rumour that I handed in my workphone with sexual material in it (dick pics, gay porn videos with me included etc). None of which is true. 

This rumour was discussed quite publicly with clients and corporates I had a relationship with (and could likely continue working with them at the new shop) in several occasions from my knowledge. 

Anyone had a similar issue in the past and has advice on how to deal with it? Worth hiring a defamation lawyer and going the whole way? Anyone want to invest equity in the case? (spoke to a few lawyers and they aren’t cheap! 😂)