Had mitral valve repair heart surgery 2months ago..is it okay if im exposed to 2nd hand smoke tabacco?

Not really: The tobacco doesn't directly affect the valve. And you dont' mention anything about coronary disease, which is unlikely given your age. But you are very young for heart surgery, and i would do everything you can - avoid tobacco, exercise routinely, and take your prescriptions religiously -- to avoid any further cardiac complications in your future.

Avoid: It would be best if you avoid exposure to secondhand smoking. Try to encourage the smokers around you to quit.

Not really. : Second hand smoke contributes to many health problems like heart disease, lung disease, and cancer, whether or not you have had mitral surgery.