Yep, you're definitely not a failure, MrsWajs! I had exactly the same thing with Mindy. Every night she would cluster feed from about 5pm to 10pm, while generally thrashing and being fussy because she was tired as well as hungry.
Lansinoh is definitely good for sore nipples. I also found if I ever got really sore that using nipple shields for a day or two gave me a chance to heal up between the relentless feeding. Taking a paracetamol or ibuprofin about 30 minutes before the evening feeding mania kicked off too seemed to help.
Also, do you have a breast pump? I found my milk supply was much better earlier in the day. So I'd pump the side Mindy didn't feed from at dawn and/or in the morning during her nap, which would yield enough milk to give her a bottle in the evening. It worked well as it gave me a chance to take a short 30 minute break, my DH a chance to bond with feeding Mindy, while she still got the goodness of breast milk. :)
Another advantage of the breast pump is that if you have one particularly sore nipple, you can use the pump on that side for a day or two and give that milk in bottles.
On days when I didn't get chance to express or couldn't produce enough, I gave her small amounts of formula instead. I managed to drop it completely after a few months once her appetite and my supply were regulated better, so a little bit of formula definitely doesn't spell the end of BFing. And while Mindy is a bit of a strange child, I think that's more genetics than the formula. 
Aside from that, set yourself up a comfy nest in your favourite chair each evening, with phone/remotes/drink/food/PC within reach, and just feed-feed-feed!
Just to warn you, during growth spurts Mindy would often feed all day! Her best one was at the 4 month growth spurt, where she fed for 18 hours straight one day, with just brief pauses while I dashed to the loo or grabbed a sandwich! 
We had our ups and downs, but made it to 6 months with breasfteeding. Though she's 10 months now, and we still use the mantra of "If in doubt, feed." whenever she cries.
She seems to be a bottomless pit!
One other thing, be wary of thrush! I suffered with it for ages, before I finally got any help. If you're getting a burning sensation in your nipples/breasts that seems to start shortly after finishing a feed and lasts for half an hour or so, then it could well be thrush. Get thee to a doctor if that's the case, and demand proper injested meds! None of the cream/gel rubbish, as it just doesn't work.