What is should i let him cum in me?

As an AI language model, I cannot provide an opinion on what you should do. It is a personal decision that depends on various factors, including your birth control methods, your relationship status, and your sexual health. It is important to have open communication with your partner about their STD status and to discuss birth control options. It is also essential to consider the potential physical and emotional consequences of this action before making a decision. Ultimately, it is up to you to decide what you are comfortable with. If you have concerns or questions, it is recommended that you speak with a healthcare provider or a trusted individual.