羽目になる|はめになる

Expresses ending up in an unpleasant or undesirable situation, often because of one's own actions or bad luck, and conveys regret or dismay about the outcome. Typically translated as 'end up (having to) do ~'.

Used in both conversation and writing to describe, usually with regret, how one ended up in a troublesome situation. It commonly follows a cause clause (e.g. ～ばかりに, ～て) and often takes てしまう to heighten the sense of dismay. Unlike neutral ことになる, it always carries a negative nuance about the outcome.

• 始末だN1「始末だ」 expresses the speaker's criticism or resignation toward a bad outcome brought about by a chain of events; it's mostly used to criticize others but can be self-mocking, and the preceding events are usually laid out first. 「羽目になる」 instead focuses on the person involved being forced into something they didn't want.
• ことになるN4「ことになる」 is neutral and can express decisions or arrangements made by others or by an organization, objective results, or inferences, for good and bad things alike, whereas 「羽目になる」 only describes misfortune one is forced into. Substituting 「ことになる」 usually still works, but the tone of resignation and regret is lost.
• を余儀なくされるN1「を余儀なくされる」 attaches to nouns and is written language used in news and official documents, objectively stating that someone is forced by external factors. 「羽目になる」 mainly follows verbs, is stylistically neutral, and usually recounts misfortunes of oneself or people close by, with a tone of regret or self-mockery.
• あげくN2「あげく」 follows a verb's た-form or 「名詞の」 and leads into the following clause, stressing the final (usually negative) outcome of a long process, while 「羽目になる」 follows forms such as the dictionary form and serves as the predicate, stressing being forced into something unwanted. The two can be used together but generally shouldn't be swapped.
• ざるを得ないN2「ざるを得ない」 attaches to the ない-form (する→せざる), leans formal, and means having no choice but to do something, not necessarily unwillingly; it can also mean having to admit something. 「羽目になる」 instead narrates an unlucky outcome one is forced into, with a tone of regret, so the two are hard to swap directly.

Unlike neutral ことになる, 羽目になる stresses an unwelcome outcome. Unlike 始末だ, which critically describes a bad end state often reached by others, it focuses on having to do something unpleasant. を余儀なくされる is formal and stresses external compulsion, あげく links a long process to its outcome, and ざるを得ない states a reluctant judgment that there is no other choice rather than narrating how one ended up there.