son is suicidal/ secual dysfunction/my helplessness

My adult son has gotten up and started exercising in the Las few weeks. His motivation us mostly to have relationships (specifically sexual).Mental health problems mean he has stayed away from people all his growing years. Now he says he has erectile dysfunction and has become very suicidal. He went if Cymbalta a month or so ago after 2 years. Thus improved his motivation and energy levels. He thought it might be the cause of sexual dysfunction. I've read that depression itself and anxiety can also be causes. He went to the GP and she did some tests,but he hasn't been back again for a month. Thus is typical. We don't have much money so every specialist appointment bankrupts me for another month or so. I work but he has no income. I don't know what to do anymore abut all thus, especially when he starts talking knives,etc.I've been here before. I am also becoming very sad and finding it difficult to cope . I del like I'm just sitting here where someone else would have thus all sorted.My son's life being so painful to him is so painful to me,I find it hard to ask or talk to anyone anymore.