OK sis -- Im going to give this a shot and inshaAllah it will be of some assistance to you.
This is solely my opinion.
unless I posted a source.
Sis from what I have read from your posts is this -- you were fully aware of his situation before you married him and I assume this also to be the fact that he hasnt told his first wife or wouldnt be telling his wife --- so you had full knowledge of this before you married him.
If this is correct -- then you pretty much knew what you were getting yourself into. It is better to be married as second wife than being single if this is all that was available to you.
see source below
Unfortunately some ppl here are quick to judge a fellow brother in islam - astaghfiruallah - however the brother does not require the permission of his first wife to remarry.
Here is a quote from the source below
"no evidence appears neither in the Qur’an nor sunnah requiring the permission of the first wife if her husband wishes to marry another wife, and therefore he is not required to ask her permission. However, he needs to be judicious in taking this decision and to weigh it carefully with respect to benefits and drawbacks and to look with the eye of wisdom at all of the considerations pertaining to the matter, and he should strive all he can to conciliate, reassure, and satisfy his first wife, in order to ease and mitigate the effect of the matter upon her"
Though the situation in the source is a little different to yours the main answer applies to you. He does NOT
have to tell his first wife but it is preferred that he treats everyone fairly and does so --- this is up to him and not up to you -- especially considering you knew what you were getting yourself into.
Now whether or not his first wife knows about your marriage to him is irrelevant to YOU and your marriage --- its relevant to HER marriage cause she doesnt know and thats to be left between her and her husband for them to deal with and the consequences etc -- its got nothing
to do with you.
What has got to do with you -- is how he performs his duty to you as your husband.
And this is where I feel he is letting you down and making you regret the marriage.
You and him are married therefore he must fulfill his obligations of supporting you in EVERY
form -- that includes financially - even though you can support yourself. (unless you waived this right at the time of marriage --- so did you agree to this b4 you married him???)
It also includes the amount of time he spends with you and fulfilling his husband duties towards you to avoid you falling into fitnah -- which was the whole point of getting married in the first place.
So if he is NOT living up to his islamic obligations to you as a husband -- then i suggest you see a sheikh for some counselling for you and your husband.
Divorce is not reccommended in islam generally however IF he does not rectify his ISLAMIC duties to YOU and counselling with a sheikh is NOT helping you and your marriage.
THEN and only after you have tried all ISLAMIC avenue
s -- you should divorce as he would be clearly failing his duties towards you.
PLease understand your duties as a second wife in islam and his duties as a husband towards you sis --- noone said this will be easy thing to live with --- however that is a decision you already agreed with before you married him -- so now you must do what is right islamically also and try to fix islamically what is bothering YOUR marriage.
It is clearly the brothers right whether or not he chooses to tell his first wife and does not concern you.
However you dont have to hide your marriage -- do not be ashamed as you ARE islamically married - unfortunately however you should expect in this day n age where people who are known to him and his first wife will think the way they think about other wives --- However, it is not your problem and remember you get their good deeds if they talk about you and also they get the punishment for accusing a chaste or loyal wife/woman of wrong doing.
So to help in this regards i suggest you strengthen your eman and knowledge in our deen and also go speak with a sheikh about how you feel and how he is not living up to his duties and go from there inshaAllah.