You will get a lot of different advice on sleep. It will probably all be good advice, but be sure to use what you feel most comfortable with and what works best for you and your baby. A lot of people don't do what I did, but with my son the only thing we could do was cry it out. A 7 month old can go all night without a bottle. (I got all of my advice from a ped and a book called Healthy Sleep Habits, Happy Child.) It sounds to me like he is just used to having this middle-of-the-night-bottle. My advice would be to give him a late night bottle, which it sounds like you are already doing, and then just let him cry if he wakes up in the middle of the night. You say he cries off and on, so that sounds to me like he actually might be ready to go without that bottle. If he were truly hungry, it seems like he might actually cry constant and hard until you gave him one. If you are concerned about him feeling abandoned, you can go to him when he wakes up and pat his back or console him in another way, but no bottle. He'll get the picture pretty quick. We could not console with our son because our presence just made him more alert and made it harder for him to fall back to sleep on his own.
So in short, I say drop the feeding. If you just are not ready to go there, try reducing the amount of formula slowly until he basically is only getting an ounce or two and then drop it. Next would be console him, but if that just does not work, then my suggestion would be cry it out. It is hard, but we only had to go through 2 nights of crying. First night was 1.5 hrs and the second night was 20 min. As a single parent, I would think it is necessary for you to get as much sleep as possible, so don't feel guilty about putting those needs high on your priority list. I'm sure your son will benefit from your good nights sleep, as well as his own. FYI-the book I mentioned is responsible for our good sleep habits. My son sleeps each night from 6:30-7:00. He's 18 mos now, but has been doing this since about 8 mos of age (I think - it is so easy to lose track of time!!) Anyway, good luck in the new year!