Depression, self harm. Discussion!

My partner is suffering from suicidal thoughts and exhibits self harming behavior. He also has social adjustment issues. He does not have healthy relationships with peers, colleagues or friends. He is also self obsessed to a great extent. It is extremely difficult to handle him when he tries to hurt himself. He is also constantly negative about all things in life (relationship, carreer,etc). He hides information at times and doesn't give straight replies to questions or tries to change the topic in case of a serious discussion regarding our relationship issues. However, he is caring to a great extent. He hides his real emotions behind humor most of the times. He also talks abstract sometimes and its difficult to understand the context. Please guide on how can I help him. I am a 24 year old female. We work in the same organization and also live nearby.