Hello, I am a Solicitor with over 19 years experience in the UK.
Thank you for your enquiry, I will do my best to advise you appropriately.
I am sorry to hear about you having to go through this difficult time.
I am sure if you had your Partner here with you in the UK, your Partner would be a great comfort to you.
There are two ways your Partner can join you here in the UK, I will set these both out below.
Visa Application as a Spouse / Fiancé - Permanent
I am sorry, you will need to wait till you have divorced your estranged husband and received the "decree absolute" (Divorce Certificate). You will need the "decree absolute” document as part of your Supporting Documentation for your Partners Visa Application as a Spouse / Fiancé. You have to prove to the Home Office that you free to are marry your Fiancé and the only way to prove that is by producing the "decree absolute".
Visitor Visa - Temporary (up-to 6 Months)
Your Partner could of course make an application for a Visitor Visa should they meet the requirements. The Requirements are fully detailed on the Home office website. A Visitors Visa is temporary for up to 6 months. This may be a consideration, as if are successful you wound have your Partner here with you to comfort and assist you while the Divorce is finalised. The disadvantage is that you would need to make a Spouse /Fiance Visa in the future and thus incur two sets of Application Fees, Flights etc.
I hope this satisfies your enquiry .
Finally, I would be obliged if you could kindly provide a rating for Just Answer, a 4 or 5 *Star would be a delightful!