Keep trying, if anyone tells you it's impossible on PS3 don't listen you do not need a PC/PS4 nor do you need an SSD in order to clear T5. I main WHM and i cleared T1-T8 on a phat 60gb PS3 over a wi-fi connection so i know it's doable.

There are 2 things you can do that actually help a lot:
1) Turn off all battle effects because they are distracting and because they can delay the divebomb markers/sound so turn off all of em, it sucks i know but i had to do it.
2) You are a WHM you don't need TP so use sprint to dodge divebombs, if you use sprint at the right time it can last you long enough to dodge all 3 divebombs you just gotta get used to it.

As you just said a couple posts ago "practice makes perfect" so keep at it and you will beat T5 in no time.