What is Reddit's opinion of Discrete Mathematics with Applications?
From 3.5 billion Reddit comments

By popularity on Reddit, this product is:

2 reviews of this product found across Reddit:

This is the best textbook for learning discrete math: https://www.amazon.com/dp/B00B6FAZ2Q/ref=dp-kindle-redirect?_encoding=UTF8&btkr=1

If linear algebra didn't make you comfortable with proofs then also this: https://www.amazon.com/How-Prove-Structured-Approach-2nd/dp/0521675995

Between those two you will be good. Unfortunately halfway through the semester is tough. If you are below a C I would drop it and retake it with better prep next time.

On the plus side, if this puts you behind consider taking on a Math or Statistics minor with the slack time. That can put you in the running for better grad school or job opportunities later on.

For Discrete Math, I would recommend Susan Epp's text. For the non-technical skills... you're on your own. :)