I already lost two and don't want to lose the other one.
- You can quote me
Not even remotely true. Rubbish.
Look into same-sex mates (or fixed opposite sex) for the pig in question. Make sure you 1) give the lone pig extra attention, care, and love in the meantime; 2) weigh him or her regularly to make sure he or she is holding weight; supplemental feed if not and 3) make absolutely sure, of course, the cat can't get to the remaining pig and/or any new mates you secure.
Yes, my guineapigs are housed outdoors and the cat was relevantley new to the area and housed outdoors, my dad dosn't allow me to keep them inside.
Your poor remaining guy is probably traumatized by what happened. You should bring him inside. He is likely more scared by all the different noises and just the slightest hint of another predator.
edit: even though your guinea pigs were just killed because they were forced to live outside?
I say possibly because I don't know your circumstances, but if you want this one to live he should be brought indoors. If you are unable to bring him indoors don't get more pigs that might be killed outdoors.
If you are able to be very attentive to your pig he might be okay without mates. Lynx provided some really good links and suggestions. It will be important to monitor him whether he is alone or with new guinea pigs regardless, and I imagine that would be easiest to do if he were indoors near the family.
(Sorry if your guinea pig is a girl, I wasn't sure).
Sorry again for your loss.
My concern is a cat bite that may have broken the skin. That would be very tough to find, if it's just a puncture or two--and cat's mouths are notoriously full of deadly bacteria.
In fact, most small animals killed by cats are not immediately killed but rather die later due to the infection.
I'm sorry for your loss, sorry you are having difficulty getting the adults in your family to understand the need for him to live indoors safely, and hope you can get him to a vet soon.
The pigs were not protected properly, sadly, and the cat wasn't either, with tragic results for the pigs. I hope the cat fares better.