It may be that, at 27, your daughters don't have the maturity or life experience to appreciate the challenges you have been through. If the topic comes up again, I would deflect talking about the past and instead have them focus on making the relationship better NOW. It is easy for them to just complain and do nothing to improve the situation. Have them suggest what they would like to do to draw you all closer. As long as you let them know you love and care for them and that you do want a better relationship, I think that is all you can do.