TSY – no surprise there for me but an interesting lesson! Hence my advice to start with fewer and slower reps. It’s a lot harder than it sounds, hey? You need to get the balance right here especially if you are working towards longer tris such as Oly or HIM distance.
Use the WU to focus on breathing maybe only 200m. Then do 10×100 off 2 mins. Try to pace at between 1:45 and 1:50 right from the start rather than 1:30 which seems to fast at the moment. See when you stroke or breathing starts to break down and note that point for reference. Once you can hold the session, then you can try to up the pace by a small fraction and/or add more reps.
But remember not to goo off too hard – first 2 or 3 intervals may well feel too easy (good) but the rest will test you for sure. Well done for the commitment and 1:35 should have you swimming near the top of your wave.