What does your friend want to do for Christ? What does your friend want from Jesus? Once one has a relationship with Jesus, things change. For example, someone did something once that I could just not forgive. My entire life had been, Forgive us our trespasses as we forgive those, and forgive seventy times seven.
My prayer was that as I could not forgive, I turned it over to Jesus to handle the forgiveness until I had the strength to forgive on my own. Took years--and sometimes Jesus still has to handle a part of it, but we got there.
If this works for forgiveness, I have a strong belief it will also work for sin. Since God is great about bringing good out of evil, I am sure He can be trusted to bring good from sin.