Unfortunately I would say no to swimming and frankly, I’d probably also be inclined to drain it as soon as possible. If that damaged horizontal piece gets disconnected from the T piece the liner will almost certainly split and the pool will be destroyed. I feel like it’s probably barely hanging on and any movement or stress from swimming (or even holding back all that water) may cause it to release.
Definitely no way to fix it without draining as the top frame needs to stay together to support the pool.
After adding blocks under the legs of my Intex with a full pool, I can say with utter certainty that there is no way to fix that without draining. I estimate somewhere to up around 400 lbs of vertical force was required to lift my pool legs to add blocks. Lots of forces in play here.
I too recommend not swimming and starting to drain immediately. I'd leave maybe 8 inches or so of water myself though, so the pool doesn't blow away if a storm comes up.
Repair complete - wrestling the new bar and T fitting in without completely disassembling the pool was no easy task and it definitely could not have been done without most of the water drained. I had to remove the vertical supports on both neighboring t sections as well, and it took a lot of geometry guessing before finally finding the correct angle to get enough space to pop the end in the bar.