Difficult adviser and personal improvements: How do I move forward?
First of all, even good writers find academic writing somewhat difficult to learn. But it can be learned. Judging from your post, you can write coherently, and don't struggle with spelling or grammar. So I don't think it would be that difficult to learn the skill.

I'd like to recommend a book. It's entertaining, and gives really good insight into what makes academic writing different from other forms of writing. I think you will find it very helpful.

Here's the book: Scientific Writing 2.0: A Reader and Writer's Guide [ISBN: 978-981-4458-75-7 (ebook)]. If you buy it direct from the publisher, you can get it DRM-free, but you have to download each chapter separately. (On Linux, you can use pdfjoin to join the chapters into one big book.) Or you can buy it in one piece from other places, but with DRM.

Another thing I suggest is that when you read other people's academic writing, pay attention to how easy you find it to understand what the author is saying. When you find an article that is especially clear and easy to read, try to figure out what about the writing works. Likewise, when you find an article difficult to understand, identify the writing problems, and think about how the author could have made it better.

I'm a PhD student myself, and one thing I found helpful for my first few papers was to write a rough draft in an informal, conversational style, as if I were writing an email to my advisor. Then I would go back through the paper and make it a bit more formal. It's a lot easier to make clear writing more formal, than to make formal writing more clear!

Finally,  point to consider: when your advisor complained about your academic writing skills, are you sure that he or she was really talking about writing, as opposed to how you structure the article, or whether or not you incorporate suggestions, or even the methodology you used in your research? The reason that I ask is that, again based on your post, you appear to have reasonable ability for non-academic writing. Advisors can have students who are less than fluent in English, or have poor grammar. Getting that worked up because a student is struggling a bit to learn academic writing this early in the game seems a little surprising.