Negative Equity, partner leaving. Advice needed

Y45_AFC

Hello,

My Partner and I purchased a property 7 years ago at which time house prices in the city was very high which was a shared equity with the house builder (85% us, 15% house builder).   Over the last few years a combination of the city struggling and a large number of affordable homes built in the area, has meant the the property value has dropped by around 50%.   My partner and I have agreed to split recently and have agreed that she will move into rented property and I will take on the mortgage myself (her income is significantly lower and not keen for her to have any stress relating to the equity), however due to the negative equity i'm unsure how easy this will be to do?

Financially I can afford to take on the property myself. Current assets is around £20k  (cash £11k, shares £17k, offset with interest free credit card until Jun 2024 -£8k),  and taking on the all bills and removing some unnecessarily expenditure still leaves me around £500 headroom each month.

The details of the mortgage/property:

Estimated house valuation:  £115k
Less 15% shared equity:  -£17k
Left on Mortgage:  £147k
Equity:  -£50k

I could use some of the cash / shares to overpay, however this will only cut the negative equity, at best, to half.   Fixed term mortgage is due to end at the end of January.

What are my options?   Is there anyway my current mortgage provider (Halifax) would let me take her name off, redo an affordability check and let me do a product transfer  rather than a whole new mortgage (which is subject to the new revaluation)?

Any advice would be much appreciated