It is impossible to give a complete answer for such a difficult problem in one post. So I have focused on what can be done now and will bring you, hopefully, enough immediate relief to cope with the situation. I have provided links to useful posts here, rather than reiterate content, as this will become too long, so I apologise for this.
Please note, this is the first step of managing this problem.
he's like my child so I want to try
This is a key issue in responding to this. This situation truly is a double edged sword. You are in a stage of extreme emotional vulnerability at the moment, and I am reluctant to suggest to people in this state to ever do anything permanently. This also, and very understandably adds to your pressure to be able to cope with such problems. At the same time, it sounds like your dog is also a source of great emotional comfort and that is something you need right now.
Quite rightly, you assume that it is unlikely, given his breed, age and behavior problems that he would go to the sort of home you would wish for him, if you re-homed him. There has been a lot of publicity about pit bulls. Unfortunately all pit bulls have been tarred with the same brush and it makes it hard for many pit bull owners and their dogs.
You have rightly observed that being left unsupervised for long periods has helped to give rise to this behavior. A dog cannot be expected to go for 14 hours without relieving himself. So he has grown accustomed to urinating close to his sleeping and eating quarters, which is counter natural to how dogs function and a common problem for dogs confined to small spaces for long periods, an infamous example being dogs from puppy mills.
He sounds like an active dog and he would be excruciatingly bored at home for long periods alone.
Best to avoid
Firstly a bit of housekeeping in some of the things that have been suggested and that you've tried.
not leaving water down during the day
This is never advisable for any pet, unless there is a medical reason to do so, dogs need access to fresh water. Besides, it takes some hours for any water that is drunk to make it through the digestive tract and through the kidney before becoming urine, so not leaving water down is not a foolproof solution.
He has never been taught to be in a crate.
We know he breaks out of the crate, but I'd like to add; it's not practical to leave a dog confined to a crate for so many hours during the day, when the owner is away. Crates are better served for sleeping, transporting and the shorter term needs to put a dog out of the way. As a general strategy to cope with your dog being bored and missing you, this generally isn't good idea.
Benadryl, many people administer benadryl to their dogs, I personally do like recommending dosing animals with human medicine, unless your vet has instructed you to do so.
There is no easy fix, which I am sure you are aware of.
First port of call is walking.
A dog walker taking the dog out three times a week, although a good idea, will not remedy the overall situation. Such a big and active dog needs to be walked as often as possible, given he has no free access to a yard.
You could commence a new routine, where you allow enough time in the mornings to take you dog for a vigorous walk before you go to work. Play a bit with him, fetching or go to an off leash area and let him have a run. Give him plenty of attention, verbal praise and pats, let him know how happy you are to be with him.
In your current emotional state this is going to be the hardest thing for you to implement. However, on all fronts, your dog's well being and your own, morning walks will alleviate the situation, somewhat for both of you. Walking releases all sorts of feel good chemicals in the brain, and although it may not change a situation, it helps both the owner and dog to cope.
Likewise do the same when you return home. This will help alleviate some of his pent up energy and boredom.
If your dog is not already desexed, do so. As a general rule, desexing will help calm a male dogs activity levels. If he is not desexed and you do so, you may find some of your previous methods will work better when he is desexed.
On the weekends, he needs to be taken out frequently for toilet breaks. Give him plenty of praise and this is the opportunity to re-house train him.
This post deals with house breaking your adult dog How should I correct my dog when I catch him drinking his urine?. I would suggest implementing the principles here.
Also create an area for him to relief himself, within the bathroom or laundry, wherever you have a washable floor and drain. As ideal as this is not, it's better to try and contain the damage.
Although there is nothing essentially wrong with your dog, he is behaving normally for a dog with his experiences, it would be well worth a visit to the vet to get some advice and possible medication. Explain that money is difficult, so that a good vet can help provide you with cost effective solutions.
Keep up the treats and bones, they will only help to give him something to do and eat. Also see rearranging the apartment to provide your dog with edible furnishings!
TV or music
A great idea, this question goes into more detail about this How effective is leaving a television or radio on to comfort dogs when away?.
Rearranging the apartment
This will require effort that is difficult for someone who is emotionally drained, but will pay dividends. Remove all cushions and portable objects from the apartment, either put them into closets, or storage. Give your dog a couple of cushions that you are happy for him to trash and destroy.
At this point you will not be able to stop him from destroying your couches and this may be something you need to tolerate for the time being. Close your bedroom door and keep this room safe. Any objects like ashtrays and the like need to be picked up and placed in the kitchen sink or a cupboard. Clear all benchtops, table tops and minimise the content that he can trash.
This is by no means a complete solution. This is a beginning, a way to improve the situation immediately. Once you have implemented this, I would suggest posting a new question with the updated developments, so the next step in this problem can be dealt with.