You don't have to get worked up about such little things.
You shouldn't take every little thing so seriously.
ーYou don't have to get worked up about such little things.
「そんな小さなことにムキにならなくてもいいのに」
to get worked up で「ムキになる」
ーYou shouldn't take every little thing so seriously.
「小さなことにいちいちムキにならなくてもいいのに」
to take something seriously で「ムキになる」とも言えます。
ご参考まで！
「そんなにむきにならなくてもいいのに」は英語で「There's no need to get so worked up about it.」と言います。もっと短くぱっと言いたい時は「There's no need to be so upset.」でも問題ありません。
ただの冗談だったからそんなにむきにならなくてもいいのに...
It's just a joke, there's no need to be so upset...
カナダ 
