If you have a relationship with this person then a conversation is in order. With understanding, repentance and then self forgiveness may occur. I would urge that you not considerate it a judgement of their past (you have no right to that position). However, we all need to make judgements to navigate the future.

Something I always say is that judgement is unavoidable. When you adopt the maxim, "do not judge people", it logically should take away your ability to judge people positively as well as negatively. When people say "don't judge me", what they really mean is, "don't judge me negatively", this is not a reasonable request, because they innately know that what they have done is likely wrong, and are attempting to influence, if not fully avoid the repercussions of their actions. As far as your specific case goes, you have to ask yourself, what are your values concerning abortion, and what are theirs? Do you think that your values are more moral, enough so that it justifies negatively judging this person? Do you have enough information of the given scenario to judge accurately? And as a Judge, would you personally consider it more ethical to be one who deals in merciful judgement, or in harsher judgement?