Just my own story, my twin and I grew up half-Korean and speaking Korean but our stuttering made both our English and Korean a bit of a mish mash so my parents decided to just focus on English after our teachers apparently complained too much. We don't blame our parents at all, but we do wish we had maintained Korean. Anyway, our life paths led me to learn Danish and my brother German. By this point (late teens) we had learned to manage our stuttering in English to a good degree but learning a new language was like being a kid again where we stuttered every other word. In short, it was a huge pain in the ass that required a lot more effort to stutter less in our foreign languages, but for us, it was possible with a ton of repetition. That's horrible that it appears to be getting worse with your native and not just the foreign language. That's not what I have experienced. I would search the subreddit for additional answers since people may ignore this question due to it's frequency, but the answers vary quite a bit and you might find some better advice. Good luck.