Please Help Me Learn English Grammar

How does an adult learn grammar? This question might seem silly, it may even seem pointless, but regardless it is something that has been avoided and left to die. The grammar elites point us back to grammar school. As if the days of elementary school and the basics are the place to start. The image of a grown 28 year old sitting like a pretzel on a shag carpet surrounded by 30 eight year olds is not working of me. I can’t go back to grammar school; after all I have a Masters Degree.

The truth is that I am too advanced to start at the beginning. I know where a period goes. What I need is the scientific break down of sentence structure. I want a complete comprehension of verbs and prepositions. I want to learn the make-up of the English language. To think that I am so eager to learn, so hungry to educate myself makes me proud. Almost proud enough to forget about the shame and embarrassment I suffer through when thinking about being 28 and not knowing the blue-prints of my own language. It can be humiliating when you place a comma in the wrong place or add an apostrophe where one doesn’t belong.

Where does an adult learn grammar? I have read Shrunk and Whites Elements of Style. It has helped, but seems to assume I know the things I should have learned between the fourth grade and now. I have read various guides to grammar and again they are informative but fall short of giving me complete comprehension.

The two main problems I find when trying to educate myself is 

1. They (grammar snobs, grammar guides, and style manuals) assume I know the elements of grammar so they focus of the common mistakes or tricks that the pros make.
2. They (educators, grammar guides) assume I am in the third grade and focus on periods and capital letters. 

Is there nowhere in the middle for people like me? Am I destined to watch the grammar boat sail away into the horizon because I refused to buy a ticket while I attended school? Can’t a person be a late bloomer, not in that I couldn’t learn but rather that I never thought it was important enough for me to learn? At the age of 24 I left a boy for a far off war and returned a man ready to fix some past mistakes. Can someone please help me?

Is there anywhere an adult can learn English grammar?