Question what do I do if my wife refuses sex .. because she say she sick ..And we only have sex once every two months...

All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.

If your wife is sick and the sexual intercourse causes her harm, there is no blame for her if she rejects your request for having sexual relations with her, since she is legally excused under this case. However, if she has no valid excuse for rejecting your request on that matter, this is considered some sort of Noshooz (i.e. disobedience), which means that she has committed a sin that would make her liable to the severe Sharee'ah penalty on that matter. So, you should clarify to her that she is obliged to obey you when you ask her for sexual relations unless she is legally excused with matters, such as menses, obligatory fasting, sickness, etc. In case she has no valid excuse and she insists on her disobedience, you have the right to deal with her as Naashiz, including forsaking her in bed, etc.

In addition, if you have the ability to marry another, you should do so; otherwise, you should be patient, adhere to chastity, keep away from places of temptation, observe much fasting, keep your hearing and seeing from the unlawful, and be busy with what is beneficial for you.

Allah knows best.