Sorry to hear what you're going through with your family.
re using an egg donor - for me it is what it is, you will never be able to change that it's not your egg, but the love you hold for that child is no different to it being your own egg baby and the fact that you've nurtured that pregnancy gives you a connection to your baby that adoptiin/fostering will never do - my blood helped create hers etc... I do look at her and wonder about our donor, but its always with gratitude and love, I don't ever think of it in a negative light. Some others may not even think ofctgeir donor at all or push it aside but I'm a pretty practical and open person. I've never struggled with using a donor, I figure my girl is unique, our family is unique. And the way I figure it, teens are always going to find things to be angry about... trust me!
You have to be comfortable with the decisions you make at the end of the day.