not regret it at allA strong way to say that one has no regrets. Depending on context, เสียใจ can also mean “be sorry” or “be sad.” เลย intensifies the negation, meaning “at all.”
TH: ฉันตัดสินใจถูกแล้วและไม่เสียใจเลย
EN: I made the right decision, and I don't regret it at all.