Did it by mistake: lỡ / trót + verb

Lỡ before a verb says you did something by accident, or without thinking, and now it can't be undone: Em lỡ làm bể ly rồi. I've accidentally broken a glass (in Hà Nội, làm vỡ cốc). It usually comes with an apology, and often with rồi or mất: Chị lỡ xóa mất tấm hình đó rồi. I accidentally deleted that photo.

Two set phrases are worth learning whole: lỡ tay (my hand slipped) and lỡ miệng (it just slipped out): Xin lỗi, anh lỡ miệng.

Lỡ also covers things you did on purpose and now have to live with: Lỡ hứa với tụi nhỏ rồi, phải đi thôi. I've promised the kids, so we have to go. In Hà Nội, and in writing, trót does this job: trót hứa, already promised.

The same word means "in case": lỡ trời mưa. What follows tells them apart. Before something that might still happen, it's "in case"; before something already done, it's "by accident". With a noun after it, lỡ means "miss": lỡ chuyến bay, miss a flight.

Compare suýt: with suýt, the bad thing nearly happened. With lỡ, it did.