be supportive but if she truly is disabled and can not work and has medical documentation go that route. Its not the easy solution but its certainly better than offing ones self. I am speaking from experience also. So she needs to also be strong enough to say she needs help and stop being proud and stupid. IT has to start someplace and getting disability is not a overnight process, so again be supportive but do not let her cave into despair or bring you into it either.
i agree with the other anon, part of this is her own fault and part of this is you are enabling her slightly by making excuses for her. If she is that severe she should be able to get it even with out a lawyer, but if not she should get one she will lose a small chunk but its worth it for the help. That is what i did either way good luck to both of you .
there is always a line though keep that in mind, boundaries are needed and especially if she is a liar, odds are she is not suicidal she just does not see any options right now, at the end of the day though if she really wants out thats on her not you. Pray for her and pray with her as well.