If she is on day 49 then it's too late for alizin injections to abort anyway, and personally, although I would consider spaying a bitch to abort, I am not sure I could on day 49.
For future reference, if you get an 'unwanted' mating, get her to the vet ASAP for alizin.
Wormer is panacur liquid, daily from day 42, so you're a bit late, but get some from your vet anyway. It isn't cheap, but you can use it for the puppies too from 3 weeks. (although I personally use drontal puppy suspension for pup and panacur for the bitch whilst she is in whelp)
Your girl is really at risk. 5 is old for a first litter. I would really suggest you buy 'Book Of The Bitch' to read up on whelping and what will happen, what you will need and what can go wrong. Things like the bitch chewing the umbilical too short can cause a puppy to bleed to death if you are not prepared for it. Bitches can also get very frightened when the first puppy is delivered and try to bolt/bite people. It has also been known for bitches to turn around and kill the first puppy as soon as it is out. You need to be prepared for all eventualities. You need to make sure you can get hold of your vet once she is in labour and have access to a car in case of an emergency. Even if everything goes swimmingly, you really need to get the vet out the morning after the pups are born to check them over for things like cleft palate (if they have one they may slowly starve to death) and that the bitches milk is coming in well, there are no puppies left inside her etc.
Your bitch really needs a scan ASAP so you can sort out wormers and puppy food for her, a good quality one. She will need several small meals if she has pups in her and once she whelps she will need lots of smallish meals per day and plenty of fluid. 63 days is right, but she needs watching 24/7 from day 58 at the latest.
Expect a food bill of up to £100 per week as the puppies grow, plus worming, bedding, toys, vet checks. Hopefully she won't need an emergency c-section, but it's more likely given her age. This would cost £1000 plus. It's a very expensive business.
Please let us know how you get on at the vets.