How to choose the delimiter for splitting text into columns?

Question

I have a DSV file and each row corresponds to one instance/piece of text as normal. Specifically, I have my own delimiter ### instead of the default (i.e., comma ,). However, when I open the DSV by using Google Sheets, these tools always display the DSV file by splitting automatically by default delimiter. It causes a mess because some columns may contain several commas.

How can I disable the trigger that splits the text into columns automatically and only use my own delimiter?

My DSV is like below:

a###b###c###d,e,f,g###h,",",j
h###i,j,k###l###m###n,"[o,p]"
q,r###s###c,u###v,w###x,y,'z,'

As suggested, I have tried to copy the content directly to a newly created Google sheet, however, I got the error as below due to the size of the content.

There was a problem
Your input contains more than the maximum of 50000 characters in a single cell.

Answer 1

With File > Import > Upload > Drag one can choose one's delimiter (though not, as far as I am aware, as in Excel the option to "Treat consecutive delimiters as one"):

So, depending upon your specific file, you may find the result this way is what you want - provided you are prepared to delete a couple of blank columns for each set of ### (if not choosing a single character rather than ### in the first place).