some of the tech savvy smart arses will give you long winded and extremely complicated advice. simple answer is yes get another number. and the best and most straightforward way is to get a basic old fashioned pay as you go for a tenner and pay cash for a tenner top up.
if you got oh then keep it hidden from her. if not even less of a problem. never let hoor know your real number or your real name or your real job or where you live. not just the address but any clue. remember they are hoors and all you want to give them is your hard cock. simples