If it was just me I would endure it but I don't want our child to copy you so stop it.
"私だけだったら我慢するけど子供がまねたら嫌だからやめて"
- If it was just me I would endure it but I don't want our child to copy you so stop it.
- It would be okay if it were just the two of us but I don't want (子供の名前）to copy you so please stop sighing all the time. (もう少し優しい言い方）
If it were just the two of us, I could put up with your sighing all the time, but we have a baby now and I don't want him/her to do the same things when he/she gets older, so please stop.
ーIf it were just the two of us, I could put up with your sighing all the time, but we have a baby now, and I don't want him/her to do the same things when he/she gets older, so please stop that.
「私たち２人だけなら、あなたがいつもため息をつくことに我慢できるけど、赤ちゃんが生まれて彼/彼女が大きくなった時に同じことをして欲しくないの。だからそれをやめてちょうだい」
If it were just the two of us, I could put up with ... で「私たち２人だけなら…に我慢できる」
この場合「私だけ」と言うより、just the two of us「私たち２人だけ」と言う方が自然な感じがします。
ご参考まで！
アメリカ合衆国 
カナダ 
