Someone misusing my picture

Hi to give you a brief I am a female who was friend with a colleague from past one year , just friend I lay srress on word friend here, very recently I discovered that he has likings for me from our common friend , on knowing that I maintained distance from that guy because I have nothing for him obviously when I just taken him as just another friend ...For you to know I already have a boyfriend n we guys are dating from past 10 yrs. now this office colleague couldn't accept the fact that I starting ignoring him and not being friendly like I was earlier with him, and since he was grudging over the fact i kind of neglecting him what he has done is out of an old common office friends get together where i happened to have danced with him, he apparently have asked one friend of his in the group / rather match fixed with one girl one close friend to click a picture while we were dancing just a mere random dance in reality but the picture has been taken in such a way that it shows closeness or some level of chemistry in between us. that girl has been used as a help there while plotting it against me, the output is close Photo which this guy now is sharing with every random person to defame me and to potray me as his girlfriend and same news he has spread across to my boyfriend in a way that my boyfriend questions my loyalty and it should lead to our breakup is his motto.... I want him to pay for his action that he has played up against me with that picture. Please suggest me what legal action can I take against him and how as soon as you read this I need an answer please. Reply awaited Please treat this as priority