You probably know it, but just in case, for me one of the best books (very nicely explaining) is Rossi: https://books.google.pl/books/about/Theorems_Corollaries_Lemmas_and_Methods.html?id=kSwVGbBtel8C&redir_esc=y

I registered an account at Beehaw 😁

You cannot think about it, since such thoughts (even if true) will eat you from inside. I was like this for a while (maybe result of fasting or trying be vegan), but most probably the cause is being tired - get as much sleep as possible, reduce screen time and try to avoid disturbing news for a while - it may help.

I like logic too, the proofs at the beginning can be done almost exclusively by truth tables and de Morgan laws (at least at Introductory level course). Anyway, best luck and fun from it!