I think the past is just a sum of our lessons, it doesn't equate to who we are in the present. It makes us wiser, well hopefully.
If someone has a sordid past, whether it be sex, drugs or bad choices & has learned what they needed to, to make them a better & stronger person then I take my hat off to them, all I ask for is honesty if it's something that may come back to haunt them & I'm involved with them & I don't think that it's my place to forgive, all I can do is try & understand or at least be unbiased & a good listener, we are much harder on ourselves than anyone else could ever be anyway.