ついカッとなってしまって。

just (now); quite (near); unintentionally; unconsciously; by mistake; against one's better judgement (judgment)

yet; moreover; and

if; when; and; with; particle used for quoting (with speech, thoughts, etc.); quoting particle; promoted pawn; indicates question (sentence end)

to become; to get; to grow; to be; to reach; to attain; to result in; to prove to be; to consist of; to be composed of; to succeed; to be complete; to change into; to be exchanged for; to play a role; to be promoted; to do ...