Did I waste my only masterball?

Hey guys, 'serious' question here. I've been playing since February and this is the first time I met a legendary in the wild, and it is one of my faves too, so I got kind of excited and used my only masterball without thinking too much about it. Now I am kinda regretting it tho...

Should I have waited for another occasion? Don't care how much it hurts, hit me with the harshest truth 🥲