Hello, everyone...

I will try to be short with my story.

My husband and I have been together since 2008 and married since 2010. My husband has a child, boy, from a previous relationship. Biological mother was diagnosed with bipolar disorders and can't ( or does not want to...I am not sure) raise the child. The child is now 7 and a half. He has been leaving with my husband and I since he was 2- when the mother decided she can no longer care for the boy and dumped him on my husband's shoulders,boyfriend at that time. Biological mother lives in another state, sees the child when it is convenient to her, makes a bunch of excuses, has the mentality of a weekend parent, is very permissive and does not pay a dime for this child. The burden of financially provide for the kid is on my husband and I. I think it is more on my shoulders than his since he has decided that the job he was having before is not the right one. He is trying to get a master's degree in healthcare.He has been depressed and angry lately due to the fact that he is not able to get into the nursing school.
With his last job, my husband was out of town for long periods of time and I had to raise the child and take the responsibility.
My mother-in-law has a very particular way of seeing the situation. She likes to give plenty of advice and talks way too much about things she does not know. When the child was given to my husband by the biological mother, my other-in-law was very upset about the way the child was raised. I need to mentioned that he was very dirty, developmentally delayed, malnourished and bratty. She could not stand the biological mother. As the child grew older, she started making excuses for the child stating things like: " Poor child, he misses his mother!" or " The situation he has to deal with- not being with his biological mother- is very damaging for the child." " I pity the biological mother because with her mental illness- she can't raise the child.' " Okay, let's but the child whatever he asks for because poor thing he is not with his mother."
I am having a hard time dealing with her way of thinking and approaching this situation.
She often tells me: " This is not your child. You should not take responsibility for raising him or providing for him."
I have no choice right now since my husband does not have a job. I must provide financially and emotionally for the child.
I don't mind that as long as my efforts are recognized and appreciated.
Yesterday, we had to meet with her at JC Penny so that we can buy glasses for the boy. Since we did not have the money, she offered to pay. She kept saying:" The child should choose whatever pair he likes since I am paying. You guys don't understand this child. This child is missing his mother.That's way he is acting out. Bla, bla, bla." This conversation made me very upset and my husband did not say anything about it. He let her go on and on and on.
In my opinion, I think the biological mother is not apprehensive about taking care of this child. I don't doubt that she loves him. But as long as the child is cared for by someone else, she can play the fun parent.I perceive her as being very insincere and opportunistic. I think she likes the situation as it is and does not
I think my husband took and is taking me for granted. And I think that I have assumed too much responsibility on raising this child. But I had no choice when he was left with me because of my husband's job.
Biological mother plays the victim role and the " I am sick, I can't raise this child" position.
At this point, I am very hurt and don't know what to do". I have to deal with my husband's depression and my mother-in-law's comments.

What are your thoughts on this?

Thank you.