Aphids on my plum tree

[Jfv]

I really am completely clueless when it comes to anything to do with gardening so I could really do with some advice on this one.
I was wondering why my plum tree had not produced any fruit this year, but then discovered it was absolutely covered in aphids. When I say covered, I mean every newer leaf cluster was covered in aphids on the under side. I did a bit of research and diluted some washing up liquid with water and sprayed the (many) leaves that had apids. I did this over a few days and a few times I did spray it down with the hose the next day or a few hours later. Many times I did not do this step though.
My tree is now shedding it's leaves to the point where I think it may become bare! Have I killed the tree? Or will new leaves grow next year? I 😫 I have so much to learn!

It’ll survive. Plants’ instincts are to survive. There’s a lot of energy and nutrient stored in roots and branches, it’ll survive one year without leaves

My damson tree did exactly this but is flourishing now. Is it in a pot? Mine was (still is) in a pot and I found there were thousands of ants in the soil! So I washed as much off as possible and put some lovely new soil in. I put very sticky tape, stick side out around the trunk in 2 places to stop the ants farming the aphids. Lots of water and feed once a week and it's looking great again.

It isn't in a pot but that is very encouraging to know there is hope in its revival. Do I need to remove the aphids completely so there are none left for it to recover and fruit next year?