Can are will i be able to get custody of my son? And can she just come in and take want ever she wants? What should i do?

My wife has tryed to kill her self 2 times in 4 months. The first time she took hand full of pills and got sent to a hospital for 2 weeks an when she got out she left an moved out of our home. 1 month later she wanted to come back, so i let her.. 2 months later she tried cutting up her arm at her moms, an got sent back to hospital. She stayed when she got out this time. Well a month later she told me she was going out and then at 12am she texts that she aint coming back. Ok so both times she tryed to kill herself it was in front of our 3yr old son , he has seen everthing, her take a handful of pill and get dragged into the hospital and the 2nd time cut her arm up an be taken off. Now she wants to pull him out of our home whenever its good for her an whenever she wants. She is not taken her meds that the dr's put her on. Her reason for leaving is she hasnt been happy in a FEW weeks. There has been no drugs involed. There has never been any violence.