It sounds like you are in a somewhat good position. Can the things you have to get past be "forgotten" by declaring a fresh start? In addition, if it is relaxing to be around you, he might be more likely to sink back into that family situation with you. So for example, be lighthearted and happy. Also, when he comes to overthink about having one of his favorite dishes for dinner. Talk about things you know he likes, etc. Be yourself but just consider what makes another person want to remain in your company and environment.