It all comes down to you - if you're afraid of what your friends might say or think, remember that they'll probably think it's amazing that you can draw at all. Often, you're the only one who'll look at your work for more than ten seconds, and also you're the only one who'll ever critisise it so harshly. I always want to support my friends online by commenting on their ig posts and retweeting them; it makes me feel good that I can be a bit of a cheerleader, and maybe your friends might feel the same?
I personally don't give out my usernames to anyone besides my closest friends because I draw a fair bit of 18+ artwork - in fact, i preemptively block them most of the time. I like having a sphere separate from my IRL friends, especially for the sexually explicit stuff!