I have not been through it, I know a few people who have. Also I had some classes on canon law and known people on tribunals.
First. I am so very sorry. No matter what else, I am so sorry this is happening to you. It is good to see you again, I wish it was under different circumstances.
The process can vary, not in any substantial form, from diocese to diocese. But the difference may be in timetables basically. It is, of course, an emotional process and would contain going over many details that makes people uncomfortable. So it can take a toll, in particular after the emotional nature of a divorce. So be ready for that.
Most diocese make it as painless as possible, but some can be less understanding. That is just an honest observation from talking to people. It would depend on who you deal with. The view is the marriage is valid until it is shown that it is not...and depending on the Defender of the Bond, that can be somewhat emotional to disprove.
In general no one is there to make it difficult...but of course, by the nature of the situation that is sometimes unavoidable.