The safest thing to do is that after you cum, hold on to the condom at the bottom of your penis while you pull out. Once your penis (and the condom!) are away from your partner's vagina, remove the condom. Tie a knot in it to keep things from spilling, and then wrap it in tissue and throw it away.
Start fresh with a new condom if you want to have sex again.
This is the safest, as it reduces the chance of pregnancy. After sex, your penis will go limp. If you are still inside your partner, the condom may slip off. This could mean that your cum would spill into her vagina.
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