IR ESA - Change of circumstances UC Area

I receive IR ESA - support Group and have been living alone in receipt of full HB and CT. My estranged husband current receives CB ESA and receives IIB. He submitted his ESA 50 renewal in March 2018 - still being paid but no written documentation regarding his award to date. He was given a cancer stage 4 terminal diagnosis of 6-9 months to live. The Macmillan Benefits advisor is submitting a fast tracked online PIP form today as he is entitled to higher rate of care and mobility. Given my husband's diagnosis he has moved in to my rented property. I understand I need to advise DWP and Local Authority of change in circumstances and this will trigger a new claim for UC. Am I right in thinking that my existing ESA will not be protected by transitional payment protection and my benefit will be slashed to the new UC rates? Will I be able to claim Carer's premium despite the fact that I am classed as unfit for work? I would really appreciate urgent advice given our circumstances.

Thank you Gordon.
We will be living as partners so his benefits will affect mine. I would be providing more than 35 hours per week care. So what deductions would be made? Is the Carers Premium £156.45 per month?

Gordon, would be living as spouses. So if I lost ESA and housing benefit does this mean my husband should make claim for HB and CT? Surely he would be given some additional ESA for a couples claim?

Hi Gordon. Spoke to Macmillan advisor yesterday to get an idea of how to proceed but need to meet up in person to finalise details. He said as you mentioned, can we reasonably show that we would not be living as partners as then his benefits will not affect mine, given that his prognosis is only 6 months to live and I will be acting in a caring role for in excess of 35 hours per week and I live in a 2 bedroomed property.

He says if we live as a couple then my ESA SG claim would be closed and I would have to claim UC and monthly payment to me would be £680 (includes housing element) and my husband's claim would remain CB ESA. My understanding then is that I would have to wait for a Universal Credit to be paid which could take 5 weeks. Also have to consider that after my husband's "passing" I would again have a change in circumstances to report and yet another adjustment to my benefit claim. I feel emotionally drained trying to process all this financial information and unfortunately the Benefit Calculators are not making it any clearer for me. I was hoping that I could retain my ESA IR until I was naturally migrated onto Universal Credit. I would really appreciate another opinion on this complex situation. Thanks.