Hi and welcome to VB
Regarding leather and other animal products that you have from before, it is a personal decision. Some people continue to use the products until they are worn out, and then replace them with vegan options. Other people choose to give them away. It depends on your own comfort level.
I have given away some leather good like a jacket I had and gloves, but for purses and shoes, I still use the ones I purchased in the past, and just choose non animal ones when I buy more.
Having unsupportive omni friends is far too common, but most of us have experienced it. That's why it's nice to have a place like VB
I don't know too much about supplements, but I would try using the search function to look for old threads about anemia.