"Only my condemnation harms me"
is not very clear. It actually suggests that nothing condemns me except my (own) condemnation, but I'm not sure this is what the writer means.
My condemnation only harms me
My own condemnation only harms me
Note that "only harms me" is still ambiguous: it could mean 1) that it only harms you and no one else, or 2) that "harm" is its only effect on you.
In any case, "My condemnation" means that it belongs to me and could be directed at myself and/or at other people.
"My own condemnation" could be the author's attempt to say "My self-condemnation" (ie, as opposed to condemnation that is directed at others), or they could be trying to emphasise that one's condemnation is their responsibility and their fault and no one else's, and/or that people have their own personal types/styles of condemnation, which could take different forms in different people.
"Only my own forgiveness sets me free"
could mean self-forgiveness or the forgiveness (that is particular to me) that I have for anybody.
The fact that the author goes from "My condemnation" to "My own forgiveness" indicates that some distinction is being made. I would assume that they mean
the condemnation that I have is harmful, but the forgiveness that I give myself sets me free