miss Her so much

Dont know if that should be posted here or not
Any way to cut the story short,was married to a stunning Domme and cuckoldress for several years ,where the best of my life,due to my stupidity we got divorced 3years ago
We started talking again several month ago and im trying hard to convince her to get married again,she almost agreed<She now has boyfriend who is married but they see each other regularly,i dont have a problem in that,but, in order that she agrees to get married to me again she said i have to talk to him and convince him that he allows her to marry me.
She wants me to do that in the presence of her girl friend and two of his buddies,which i find very embarcing and humiliating but im willing to do it

Can anyone please help me what to say and do to convince him to approve of our marriage,she says he is very possessive and a bit dominant with her

update?