Can We Prevent From Having Aids If We Have Sex With A Condom On And Having Anal Sex....?

If you think, but are not certain, that you or your partner has HIV, then you should get tested ASAP, before having sex with anyone, regardless of whether or not you're using a condom.

If you know for sure that one of you is infected, then you/they should be under a doctor's care for it. Find out how well-controlled it is. The better it's controlled, the less likely transmission becomes.

That said, the answer to your question is both yes and no. Yes, a condom is the only proactive way to block the virus from being transmitted through sex when it otherwise might be. However, even when used correctly, condoms have about a 2% failure rate, so it is not bulletproof.

Still, HIV absolutely does not mean you have to give up sex forever. Between staying on top of it with good treatment and responsible, proper condom use, you may not be able to completely eliminate the risk of transmission, but you can reduce it to very little. As long as everyone involved is informed, and that's good enough for all of you, then go for it!

Also, if the condom breaks, then there is a treatment which has a chance of killing the virus before it can establish a reservoir in your body, but it needs to be administered at a hospital as close to immediately as possible (the trick to it is, like I said, purging the virus before it can establish a reservoir), and it's disgustingly expensive if you live in the US. Still, it's useful to be aware of in case of an emergency.