Reddit mentions of The Path To Awakening: How Buddhism's Seven Points of Mind Training Can Lead You to a Life of Enlightenment and Happiness

In the Tibetan tradition there's the gradual training of Lojong. The core practice there is to realize that there's actually no difference between us and anyone else, step by step becoming truly impartially loving. He wasn't a Buddhist, but I've always liked Ramana Maharshi's answer to the question how we can really benefit others. He simply asked Which "others?"

There's many books on Lojong and it's best to find a living teacher to guide you to really get into it, but I think The Path to Awakening by Künzig Shamar Rinpoche is an accessible book on the subject.

>can it somehow be reversed and I can save myself from a lower realm rebirth?

Of course you can. That is why Buddhism exists in the first place - to help beings liberate themselves from the clutches of samsara.

I would highly suggest finding a local Buddhist center in your area and even meet a qualified teacher. It would help you immensely on your path. Check out online if there is anything around you and learn from them.

If you consider yourself a practical person and you feel that meditation appeals to you, then I would recommend reading a great beginner's book from the Tibetan master Shamar Rinpoche - The Path To Awakening

It should answer all of your current issues and help you find the key to liberation and enlightenment.