I (28f) have betrayed my boyfriends trust (28m] by sharing info with his mother (57F), how do I fix this?

Hi all,

I have hurt my boyfriend of 10 years by sharing information with his mother that he did not want sharing. I feel awful and I didnt mean to cause this.

My boyfriend has got into a hobby recently that he is embarrassed about. I personally think its wonderful and ive also got really involved in it too. I get why some might judge the hobby but I do believe if its not hurting anyone its noones place to judge. My boyfriend has said on multiple occasions that he does not want his mother to know as she will judge him and this has been a key point of anxiety for him.

I saw his mother yesterday and I was talking about coming up to see them the next day with boyfriend. I said we would be in 'x' area but might come to them after as its so close by. Then came a flurry of questions from his mother, sister and brother in law, why are you going there? What shop are you going to? What is it called? Etc. The reason we was going to this area was to a shop, that was for this hobby. I wasnt expecting a flurry of questions, so when asked i said awh yeah we are going to a shop, its for video games (as a cover) and its called x shop. I just didnt know how to handle the questions and i definitely should have just said we were seeing friends or something but honestly, my brain didnt think as i had already said i was working from home and was doing this on my lunch break. Sadly this isnt the first time this has happened with his mother, I just get flustered and really struggle to think what to say except the truth which means i let things slip to her that i shouldnt.

I came home and explained what happened to my boyfriend, and he is truly hurt and upset. Ive suggested saying its me into the hobby or something but it seems to make him angrier. I honestly dont know what to do and how to make this up to him? Or even on how to prevent this in the future. I just need some advice on how to heal from here? As ive never seen him this hurt or upset.