I started my therapy today and joined somea group session.

A group session = a specific session that happened at a specific time
Some group sessions = several different groups dedicated to different topics

It' was actually my husband 's idea, and he is also using the app as well.

It was his idea in the past, so this sentence needs to be in the past tense

The comma splits the sentence into 2 seperate but linked ideas. Other examples --> I like pizza, but I only eat it cold. I had a great idea, but I didn't write it down so I forgot it. Etc.

I don't ha've never experienced anything like this before so I was so worried that I can'twouldn't be able to understand what else people were saying or that no one canwould be able to understand my English, since my husband always say I need to improve my English.

"Can't" is present tense, but this sentence needs the second conditional ("wouldn't be able to") as it is talking about a potential but unlikely future outcome. In this case, it's unlikely as you have already done it and it didn't happen. The same for are-->were and can-->would.

For more information:
https://learnenglish.britishcouncil.org/grammar/b1-b2-grammar/conditionals-zero-first-second

https://www.madonna.edu/resources/writing-center/online-tutoring/Conditionals.pdf

But it's has been such a relief that I joined.

I used limited vocabulary , but people canould still understand me , and they doidn't think I haved a strong accent which might becould make it difficult for them to understand me.

You could also just remove the "which could make it difficult for them to understand me" as it's a bit redundant, and this would make the sentence more concise.

I almost cried when I was speaking, and I canould tell my voice iwas shaking, as well as my hands.

This is an event that happened in the past, and first part of the sentence is in the past tense, so the second half needs to be as well.

You could also phrase is as: "and I could tell my voice and hands were shaking."
Were is used here since it's now plural (voice and hands)

The fact that I joined and spoke voluntarily already makes me feel thatlike I'm still capable of controlling my life.

"To feel like" is a super common English phrasal verb, and fits better here. But what you have written is not technically wrong.

On the other hand, seeing people arewho have been prostrated with grief for months or even years also scares me.

Prostrate does fit here, but it makes me think more of its other meaning, which is to lay face first on the ground. I think "overwhelmed" or "incapacitated" could be better alternatives.

The fear of losing my husband - who might be the first one and last one that I would be able to develop a deep relationship with, - just stuck in my mind.

I hate romantic dramas but I do feels like my life is becoming a drama, which. I wish that someone who watching this drama canwhoever's watching would skip this heartbreaking part, go to the final episode, and tells me what's gonnaing to happen in the future so I can stop thoseall of this meaningless worrying, and stop meyself from making any stupid actions that I will regret infor the rest of my life.

This sentence is super long, so I tried to break it up a bit.

Gonna is very very informal, its better saved for spoken casual conversations or texting.

Me and my husband, we both have our egos, and I know that if we end our relationship now, there is no way that we will meet or reunionte in the future.

Maybe reconcile is the word you are looking for here?

Our pride doesn’wouldn't allow us to do it.

Hypothetical situations need the conditional tense.

Iphone or google Smartphones hasve a function called something like memory reminder or something,, where basically ithey will show you the pictures you took aton the same day in the pastrevious years.

He told me today that he switched it off and doesn't want to see our old pictures.

SIt was such a heartbrearking moment for me when I heard ithat.

I can't delete or even think about throwing away all his stuff, cause I think I want some evidences to show that we did create something nice and beautiful in the past.

So when I looking at couples who shared over 30/-40 years or even longer marriage life together ed, I truly think that's so impressive and remarkable.

No matter how many books I read before, how good I am at self-learning, how many traumas that I went through