I'm sorry, but I feel soooooo bad for your eldest child. You are hurting her so much. You're damaging her, not just now, it will last her entire life. You're emotionally abusing and neglecting her.

You're teaching her that she's worthless and doesn't deserve love. After all, if her mom doesn't love her then who will? Furthermore, it's going to built resentment between your daughters. Your eldest will notice how much you love your other daughter, and it will create a wall between them.

I am glad that you're aware of this and that it's wrong.

Some of the things that you've mentioned that she notices are things that you CAN in fact train yourself to do. Yes, it might be hard. But it's the right thing to do for your daughter; you're responsible for her health and well-being, which includes emotional.

Instead of calling out goodnight to her from across the room... go sit on her bed and read her a story. You can do that with minimal physical contact. Give her a kiss goodnight.

Initiate scooping her up into a hug when you pick her up. Start making yourself do everything with your eldest that you do with your youngest. If you can do it with one you can do it with the other. Over time it should get easier for you. Maybe even you'll start to love her once you stop pushing her away.

A good motivation for you should be what you noticed between the similarities between how you feel about yourself and your sister. Do you really want any of your children to feel the way about themselves that you feel?

I'd definitely go and look up a therapist for yourself. Try to find a family one, so that they'll be more used to helping families - you can start with just yourself, and perhaps branch out to including your daughter if the therapist thinks that would be beneficial eventually. She could certainly use a counsellor herself, because she's likely not willing to talk to her dad about you just in case he starts to treat her the same way; it's a legitimate fear for her to have because you're supposed to be the two people in the world she should always be able to trust and count on to love her, and you're failing her massively in that area.

I'm sorry if anything I say sounds offensive, but I really really really feel empathy for your daughter.