あまり

After a verb in the dictionary form, or a noun with の, あまり means "out of too much": a feeling or a concern goes so far that something happens which nobody intended. The word in front is usually a feeling or a state of mind – worry, joy, nerves, love.

The second half is what happened, or what tends to happen. It is not a request or a plan.

• × 心配するあまり、電話してください → 心配なら、電話してください

This is written or careful Japanese. In conversation, ～すぎて says the same: しんぱい心配しすぎてねむれなかった眠れなかった.

あまりの + noun + に

Before a noun, あまり takes の, and the noun takes に: "with such [noun] that". The noun is a quality or a feeling, often an adjective turned into a noun with さ.

Before an adjective

Placed in front of an adjective or verb with no negative, あまり also means "so ... that". あまりに and あまりにも are the more common forms here and get their own points. With a negative after it, あまり means "not very" instead.