I'm sorry to hear about the hassles you are encountering dealing with your late father's estate. Being an executor can be a lonely and thankless task. The only reward is in knowing you are doing what your late father would have wanted.
If your solicitor hasn't already advised you of this, you are entitled to recover any costs incurred maintaining your late father's property in a saleable condition including insurance, maintenance, utility bills, security, etc. As executor you have a responsibility to do this but you are not expected to be out of pocket in your endeavours, so keep all receipts and pass copies to your solicitor.
As executor, your responsibilities are to gather up the constituent parts of your late father's estate, pay any creditors (legal, Revenue, estate agent, executor costs, etc) and divide the residual amongst the beneficiaries, as per the the wishes expressed in the will which has now gone to probate.
If your sister has effectively opted out of being kept informed as to progress, keep a diary of your attempts to communicate with her and her response, if any, and again pass these on to your solicitor.
AFAIK, unless your sister takes a High Court action to have you removed as executor, there is nothing she can do. It a shame that the estate has been and apparently continues to be a divisive issue, but IME, its not unusual.
I'm not a lawyer, but have been an executor. I hope it works out.