Should I stop learning a third language so that I won't get rusty on my second one?

I'm a native Portuguese speaker that has learned English years ago, since then I've improved upon it and felt fluent , but, about 6 months ago I started learning Japanese, I know how to read hiragana, Katakana, some of the N5 kanji and I know the grammar behind particles and verbs, all was well until I started to try having thoughts and daydreaming in Japanese, I feel like my English proficiency has decayed some 20%, it feels mind shattering feeling like you forgot how to perform a task you were once praised for, my vocabulary has taken a hit and so has my reading skills, I was trying to remember the name of a song, I came up with "heir of Grievance" and "heir of grieving", the name of the song was "heir of grief", I had forgotten the word grief, I still need to focus to remember it, I'm in agony because of that and I don't know how to proceed, it feels like I'm disfuncional and can't do English right anymore, I have a feeling about 10% of this post has gramatic or vocabulary errors, I don't know if it's just my anxiety speaking out loud, but I have no motivation to study japanese anymore with that thought in the back of my mind, I need advice of any kind

Edit: in 15 minutes ish you guys managed to pull me back from my anxiety Crisis and motivate me to continue learning Japanese, thank you, thank you a lot, I've found learning Japanese a lot of fun, tho languages and self worth are tied closely in my mind because of how everyone used to praise my English, if anything I should worry more about breaking that tie than about getting rusty in english, thank you again polyglots of reddit <3