Unfortunately, it is time for more drastic measures. Regardless of why your mother is acting this way it is time for a very serious conversation with her. At 22 it is time for you to consider moving out of mom’s house. Let mom know that she has crossed a line and that having your own phone paid for by your own money is the direction you are ready to go in with all of your decisions concerning her meddling. I am sure she has your best interest at heart, but the way she is doing it — and her lack of boundaries with you — can’t be tolerated. I would invite your mom to come with you to a therapist to talk about this. (Send it by text, email, snail-mail, etc.) You are not 15 and she is treating you like you are. If she is willing to go with you then I would air your complaints there and have the therapist manage the discussion and resolution. If she is not willing to go keep the appointment anyway as you may want individual therapy to help you plan moving on.
The core reason you need to take such a strong stand is that your mother cannot (at your age) be responsible for deciding who is the right person for you. This time it is age, next time it may be his education, or his vocation, or, or, or. She may not be happy with your decision, but it is your decision, right, wrong, good, or bad. It is you who gets to decide who you spend your time with.