Is there really anyone who thinks its ok to cheat on your bf, potentially expose him to various illnesses, and then deal with the possible consequences afterwards. No ones needs trump the responsibility to ensure you don't compromise someone else's health unnecessarily. And I am sure the poster knows that, and is just looking for justification to act in an completely immoral way.
If you think your need for bb sex is so strong then speak to your bf first. Let him know it is important to you and give him the opportunity to make the decision about it and the possible consequences for his health. But if he says no, then you have to either abide by that or leave him. You have the right to make choices about your health, but not his.