Ouch! Maybe take some baby asprin to protect against clots. (As pointed out by some, they can be a problem!)
Good luck, sorry about your Opo plant! (I tried some I bought from the Oriental Food store....it was mostly pithy, at least the way I cooked it!)
Opo fruits have to be used before mature, or, yes, the large core is “seedy” almost like an apple core, the skin is tough, and what remains between the two may get pithy. Young, it’s all “tender and mild”, like a very oversize young cucumber.