@sahmads,
Talk to the second woman's family (I am assuming you are interested in her? If not, then I'll change my advice). Explain that you were incompatible with the first woman chosen for you, and that you wish her well but there is nothing between you and that engagement is broken. Explain, also, that you want to marry their daughter and have every intention of being a kind, loving, and faithful husband to her. Humbly apologize for not coming clean earlier about the earlier engagement and express your hope that you can be the son-in-law they want, if they give you a chance.
Then, if they accept you and you marry, live those promises.