Sorry to hear about your husband's mental health issues and your present situation.
I don't know whether his current behaviour is to do with his mental health or not, but maybe he should speak to his GP about this if he hasn't done that already. I know you have said you have both discussed this, but maybe you need to reiterate to him how badly this is affecting you and set some boundaries. Although I know this is quite difficult to do.
My husband is incredibly needy a lot of the time, but this is to do with his Personality Disorder, though he doesn't check my phone, he does text me a lot if I am out somewhere and is constantly looking for reassurance from me. I do appreciate that you feel trapped as I do feel this way at times too, but also want to support my husband also. It is really difficult living with someone who has a mental health issue.
I would definitely encourage him to get some form of help. It is important also for you to look after your own well-being and keep seeing friends/family and maybe even confide in them.
Sorry I can't be of more help, but I'm sure others on here may have some advice too, although it is a quiet forum at times. I wish you and your husband all the best. Aileen.