Will you be sitting with your friend (I assume you will). You can take your cell phone and ask people to call you at certain times so you will have an excuse to go somewhere to take the "private" phone call. If you don't want to stay, make up some "crisis" that is "forcing" you to leave. Be polite and kind (which I'm sure you would anyway) so your friend won't have any reason to believe you're "demonized" or unduly "under the influence of 'Satan.'" I understand your feeling that you "must" go, and that's okay. Judt don't take anything seriously. AND don't let your friends sense of panic draw you in.
If you're having trouble making friends, take a class or join a club (Toastmasters would be great!) so you meet new people. Look in the newspaper or online for events in your town you might like to attend. There are many ways to meet people besides going back to the Kingdom Hall. There are some great people out there you'll relate to. Have you ever attended an Apostafest?
Best wishes!