OP you're considered vulnerable if you have diabetes and can register here for help.
I understand that you can't talk on the phone right now, that's ok as there are email and chat facilities available to you. It sounds like you're in an abusive relationship and you need to reach out for advice and support.
Deep breaths OP.
I don't know where in the UK you are but here is available support. They all have ways of contacting them either via email, text or live chat:
England
National Domestic Abuse Helpline – 0808 2000 247 or www.nationaldahelpline.org.uk/Contact-us
The Mix, free information and support for under 25s in the UK – 0808 808 4994 ·
Women’s Aid – including Live Chat, email, the Survivors Forum and local services: www.womensaid.org.uk/information-support/
Northern Ireland
The 24 hr Domestic and Sexual Abuse helpline is open to women and men affected by domestic abuse or violence. This free telephone service is available 24 hours a day, 365 days a year:
Phone: 0808 802 1414 (Freephone) · Email: [email protected]
Local services: www.womensaidni.org/get-help/local-groups/
Scotland
Scotland’s 24hr Domestic Abuse and Forced Marriage Helpline: 0800 027 1234 or www.sdafmh.org.uk/
Wales
The Live Fear Free helpline provides advice, support and referrals 24 hours a day, 7 days a week, 365 days a year to anyone affected by violence against women, domestic abuse or sexual violence in Wales. You can contact the Live Fear Free Helpline on:
Telephone: 0808 80 10 800 · Live Chat Service: gov.wales/live-fear-free
Text: 078600 77 333
Email: [email protected]
Local services: www.welshwomensaid.org.uk/information-and-support/find-your-local-service/
You ARE allowed out to collect medication as that is counted as essential. Please stop limiting what you eat and taking your insulin as you'll make yourself more susceptible.
There is a support thread here where you can get advice and talk while in lock down with an abuser.
Please check out Facebook and look on your council website for local community groups who are supporting the community.
Here is some information from Mind on mental wellbeing.
There are refuges available should things get worse OP and please dial 999 if you feel threatened or you believe things will become violent.