That sounds exhausting :( Well done for coping for as long as you have.
I have to say up front that I don't have triplets. I have twins, who for the first four months took an hour to breastfeed each, and each started every 2.5 hours. So I basically fed DT1 for an hour, fed DT2 for an hour, and then had 30 mins to myself before DT1 woke again.... For 3 months. Things then spread out a bit, but from 4 months to 2.5 years it was pretty much bedtime feeds from 7pm and then 12.30 (DT1), 1am (DT2), 3.30am (DT1), 4am (DT2), 5.30am (DT1) and 6am (DT2) :( Not bad feeding patterns for each child, but a killer as the mum of both :(
First question has to be about feeding. Are you breastfeeding or bottle feeding? If you don't have to do all the feeds then you need to ask your DH to help. Yes, he works long hours, but as a working mum of twins, I assure you working out of the home is less exhausting than being a SAHM to multiple infants. If he is able to feed the babies (or even one/two of them), then he needs to step up in the evening. It really isn't unreasonable to ask him to feed the babies that wake at 10pm and 11pm, meaning he stays up til 12pm and you get up then to feed the last baby. He gets to sleep from 12pm, which includes the majority of "night hours", and you get to sleep uninterrupted from 8pm(?) until 12pm. I admit there won't be much time to see each other, but that's life with multiples in the very early years IME. If your DH start to do the 10pm and 11pm feeds, the. You could maybe start to wake the third baby at 11pm to feed alongside DH, to make the feeding more companionable and to mean you can sleep from 12pm instead of 1am.
If you are breastfeeding all three, then hats off to you! Being responsible for all the feeding shouldn't mean you shoulder all the night 'stuff' however - ask DH to stay with the babies until 12pm, waking you only to feed. There is an immense difference between sleeping while you are 'on duty', waiting for them to wake and feeling responsible, and sleeping when you know it is someone else's job to respond to them. Make that your DH's job from 8pm to 12pm.
Making DH step up until 12pm will make your DH tired. But not nearly as exhausted as you are. I remember going back to work when my DTs were 12 months and feeling so so rested. I was still feeding to a punishing schedule, and I commuted 2 hours each way on top of full time hours, but it was a rest to not be responsible for their lives. The commute was a restful time to get online shopping done or to read, lunchtime was a time to eat without a baby attached to some part of me, and the people I spoke to were responsible for their own toileting/feeding/safety. Your DH might well work long hours, but I guarantee that whatever his job, it holds less responsibility than keeping three babies alive and well.
I have rambled. But please ask for help from your DH, and please don't expect to be able to manage your triplets alone without any help. While DH I at work, you manage all three babies. When he's not at work, it really shouldn't be that he is 'off' while you continue to manage alone. At the very very least, he needs to be cooking/cleaning/washing oh god, imagine the washing from triplets after work so that you can sleep any chance you get in the day.
Ask for help. You are doing an amazing job, but an out-of-home-job really doesn't absolve your DH of long hours at home too....