This is the adjective from self-pity: full of feeling sorry for yourself, and showing it. It describes people and also the things they produce — a self-pitying tone, a self-pitying letter, a self-pitying song, self-pitying nonsense. In fact it attaches to voices and writing more often than you might expect, because the word is usually about how something SOUNDS: the long sigh, the 'nobody ever helps me', the story told so that you will feel bad for the teller. It is always disapproving, and it is a real put-down. Two useful patterns. First, it very often turns up in denials — 'I don't want to sound self-pitying, but…' — because English speakers are so worried about seeming that way that they say this before complaining. Learning that phrase alone will make you sound natural. Second, it pairs with 'a bit', 'slightly', 'so' — 'I got a bit self-pitying last night'. Used about yourself, and in the past, it becomes gentle and even funny; used about another person, to their face, it is sharp. Same word, and the difference is only who it points at.