DEAR ABBY: I’ve been best friends with “Mary” since we were 13. We’re 23 now. We tell each other everything and are as close as sisters. We went to high school together, but I graduated and Mary dropped out in senior year with the intention of finishing up later. She never did. She does want a GED, but her lack of a degree hasn’t been a big issue because she got married and had a kid, and her husb…