I know it is so hard to mentally get past everything you have gone through and it's even harder to not think it will come back so your mind is looking for every fail safe thing to do or not to do to protect yourself. HPV is already in your system and it didn't just disappear because of your treatment. The trick to HPV is that you need to keep your immune system strong so that if it does become active again that your body can fight it like most people. Having sex with your husband will not make it become active again as it's already in you. Hpv can lye dormant for years.
If you feel that wearing a condom makes you feel safer then go ahead but in the grand scheme it will not make a difference. What will make a difference is that you try to live a balanced healthy lifestyle and keep stress at bay. In time you will feel safe having unprotected sex with every clear checkup. These things take time. The hardest part of this cancer is what it does to you mentally and emotionally.
Start by doing some research on HPV or speak to your dr about these things. You will get there through time and patience. Be kind to yourself and take each day as it come and try not to worry about Hpv as 85% of sexually active people carry one form or another.