First, take a few deep breaths and try to stay calm.
You’re already doing a great job of keeping yourself safe by regularly using protection, and there are lots of things you can do reduce your risks of STIs and, if relevant, pregnancy.
1.) Try to squeeze out as much of the semen as possible.
2.) DO NOT douche – this can cause irritation and/or abrasions, which increase the risk of infection. This also pushes the sperm higher in your body and can increase the chance of an unwanted pregnancy.
3.) If you can, take a day or two off of work for the same reasons.
4.) Try to figure out the risk-profile of your partner: Ask him when he was last tested, when did he last have sex without a condom, receptive-anal sex, intra-venous drug use…etc. You can also call him the next day or later that day, once you’ve calmed down, to ask him and generally assess your own risks & vice-versa. If possible, go to an anonymous testing site together, or run to a CVS or Walgreens and pick up an ora-quick self-test for HIV. This can give you peace of mind and also help you evaluate the best options for taking care of yourself.
5.) If the person is high risk, Preventative care measures may include Post-Exposure Prophylaxis for HIV, preventative treatment for other STDs (like Syphilis & Gonorrhea) and Hepatitis B vaccination may make sense.
6.) If you suspect that your partner may be high-risk, go to an STI clinic as soon as possible after the condom breaks. The sooner preventative measures (like Plan B and Post-Exposure-Prophylaxis for HIV and other STIs, if relevant) are taken, the more effective they are. And Plan B and HIV-PEP are not effective after 72 hours.
7.) Get tested 2 weeks and then 3 months after the condom break, and sooner if you experience symptoms. Some STIs may take a while to show up on tests. Also keep in mind that while transmission risks may be low for HIV, they are higher for other STIs.
8.) If your partner engages in high-risk sexual behavior or has HIV, (especially if he is HIV-positive but is not yet in therapy), a four-week treatment with HIV medications to reduce the risk of contracting HIV may be useful (HIV-PEP). You can consult a doctor for PEP at an emergency room or specialty clinic [Howard Brown (Chicago), Callen-Lorde (NYC)] to get advice on what to do, as well as a PEP prescription if that’s the right option.
9.) Know that the risks of your partner being HIV+, and the risks of you contracting HIV from a single unprotected sex act with someone who is HIV+, are both very low.
a.) If you are female and have unprotected vaginal intercourse a man who is HIV positive, there is a 1/1000 chance that you will become HIV+.
b.) If you are a man and have unprotected vaginal intercourse once with someone who is HIV positive, there is appx a 1/2,000 chance that you will become HIV+.
c.) If you are the receptive partner for anal sex once with an HIV+ partner, there is a 1/200 chance you will become HIV+.
d.) If you are the receptive partner for anal sex once with an HIV+ partner, there is a 6.5/10,000 chance you will become HIV+.