"PREVENTION IS BETTER THAN CURE", pulmonary tuberculosis
is highly contagious and infectious . This is caused by droplet infection from sputum of patient and also airborne bacteria causes tuberculosis . When a sputum for A F B +ve patient cough
or talks to some one or sneeze or exhale air borne bacteria comes out from mouth and nose and spread into nearby air and in this way tuberculosis spread from person to person.
At least 4-5 feet distance is necessary for prevention.
Beside this linen , clothes , bed sheets , covers, utensils and bed sharing should be avoided till patient is sputum +ve for A F B.
Since your friend is living with you so if possible , change the room .
Second point in your case is get (these tests are for you for precaution) in XRAY chest , blood for C B C , E S R ( if very high e.g.> 100 mm in 1st hour ) , sputum for A F B ( if sputum present in your case.).
Hope this will be helpful for you.