"He was only made to ~"
"he" 「彼は」
"was only made to ~" 「〜だけさせた」
"His mother only made him study and I did all the housework. So he grew to be a pain in the ass and a terrible cleaner. He said he was sorry."
「旦那さんのお母さんが勉強だけさせてて家の事は全部私がしてたから、彼は掃除するのが下手で面倒臭がりな人間に育ったの。ごめんねと言ってた。」
The only thing I ever encouraged him to do was studying, I did everything around the house. As a result he is not very good at cleaning and he is a bit lazy too. I'm sorry.
「…だけさせる」は to let someone do ... のように言えますが、この場合は次のように言った方が自然な感じになります。
ーThe only thing I ever encouraged him to do was studying, I did everything around the house. As a result he is not very good at cleaning and he is a bit lazy too. I'm sorry.
「彼には勉強だけさせて、家のことは全部私がしてたから、彼は掃除が苦手でちょっと面倒くさがりやなの。ごめんなさい」
The only thing I ever encouraged him to do was ... のように表現すると良いでしょう。
ご参考まで！
オーストラリア 
カナダ 
