There are many, many labs that do testing through the mail, all you need to do is Google "Parrot DNA Testing" and you'll find dozens and dozens of them. All you have to do is order a test-kit from them (usually they cost between $20-$30 USD, so they're very cheap), and typically they have you pluck a couple of fresh chest feathers, send them in, and in a week or two they mail you the results. It is a very good idea that you know for sure what you need to expect, even though they are now separated, because females still can lay infertile eggs, so regardless of the situation you're in, even if you only have one bird, you should always know their gender so that you're prepared for any of the serious conditions that can result from egg-laying, such as Egg-Binding. Just an FYI.
As far as your situation, I sympathize greatly with you, I know it must be difficult to lose your best friend, and then to also have the new bird you brought into your family seemingly hate you as well. However, this is a great example for anyone who is reading this as to why you should NEVER, EVER, EVER bring home a second bird FOR YOUR FIRST BIRD, because you think "Your bird is lonely" or you think that "Your bird wants a mate", etc. I know that this is not why you brought the second bird into your home, but we see people asking questions about getting their bird "a friend" every single day, and this is exactly why we try to convince them that they should NEVER get another bird unless it is because they want another pet bird for themselves, and unless they are going to immediately keep them separated, and also realize that the outcome may just be that they lose any bond that they have with their current bird.
Birds are very much like people in the way they form bonds/relationships with others. And the fact is that birds will bond extremely closely with their person/people when they are the only option they have, but if and when there is another bird available to bond with, and if they like each other and want to bond closely with each other, then they are naturally going to prefer the bond with one of their own species to the bond they have with their person/people. And a lot of the time people actually end-up with the total opposite result that you have, they bring home a second bird and even after many months to years they either don't like each other, simply tolerate each other, or they just hate each other and are aggressive and violent with each other, and cannot be put together at all, even while supervised. You got the result at the total other end of the spectrum, the new bird and your current bird eventually learned to like each other, and eventually this casual bond turned into an extremely close bond, and they were also allowed to house together, and they then became each other's mates, whether same-sex or opposite sex, that really doesn't matter much, they are extremely closely bonded with each other...And unfortunately as a result, your first bird no longer wants to be boned to you at all, as all of his attention is focused on his new mate, and this also goes for the new bird. So now you've essentially got a pair of Macaws that are intensely bonded with one another and have no room for a bond with a person.
As already stated above, you need to sit down and think about what you want to have happen here in the end, and what your goal for your relationship with both birds is. If you want to try to get that close bond that you had with your first bird back, then you absolutely have to break the bond he has with the new bird, period. This is why when you see people selling "breeding pairs" of birds their ads clearly state that they are "breeding pairs, not pets", because as long as these two birds have this bond, there's not going to be much room for you.
Separating their cages was step one, as they cannot be housed together and then be separated every time you want to try to spend time with one of them, as you'll only cause them to be protective of one another and that's when you're going to get bitten. I'm sure it was quite shocking when your bird, which you once were closely bonded with, bit you hard. I can't even imagine having one of my guys bite me like that, I'd be devastated. But it's a normal reaction from a bird trying to protect it's mate. You have to realize that right now he only cares about protecting his new mate from harm, and that includes you. There's also usually an element of jealousy involved in this type of behavior as well, as they certainly are not creatures who like to share their mates with anyone or anything. You need to work with each of them one-on-one, in a separate room from the other bird and their cages, where the bird has no distractions, no protective behavior, no territoriality, etc.
It's quite possible to get your relationship with your original bird back, it's just going to depend on whether or not you get his bond/relationship with the other bird to be one that is friendly, but not a close, mate type of bond. Sometimes it happens quickly, sometimes it never happens. Sometimes you end-up not being able to allow the two birds to have any contact with each other ever again, sometimes it works out that simply putting them in separate housing works. All of these situations are completely different, and can end-up with all kinds of different outcomes. But regardless, it's going to require you to commit yourself to working with them alone, one-on-one, away from each other and away from their cages, every single day, as well as trying your best to include them in your daily life as much as possible. Hopefully you are going to be able to "hit the reset button" and start over with your bird, and then also form some kind of positive relationship with the newer bird; it doesn't always end-up that way, but it's completely possible...
