A late in life divorce after long marriage is both economically and emotionally devastating, especially if there are insufficient assets to provide for reasonable standard of living for both parties.
Firstly find out exactly what you are entitled to out of existing matrimonial assets and liabilities and pensions. The starting point is 50:50 for long marriage in negotiations. Then assess your future income and needs. Until you know where you stand, you can't really make any decisions yet. At this stage do not worry about children's possible inheritance as they have no legal entitlement to anything, and can only have what is left to them. Most children would not wish you to be miserable if you have other choices, but whatever you decide to do may come as a shock to them.
Living separately in a shared house is extremely emotionally taxing, especially for givers living with takers and doesn't really give you any freedom to form new close relationship if that is what you intend to do, and also you will need to reach an agreement on future bills/cost shares. You are not the only decision maker in this situation, and also need to bear in mind that your husband may be difficult to deal with, whether you stay or leave him, which is another reason need to find out your entitlements, and what you are going to do for future income in case he eventually wants to divorce you. .A state pension doesn't go far if you are renting, as the rent levels for housing benefit single people are very low, usually set a less than market rent for one bedroom flat.
Whatever you do do not rely on meeting someone who can provide a magic wand to whisk you away to a happier place. It is usually easier to obtain a clean break from your marriage without the complications of infidelity entering the equation.
If you decide to carry on as you are, do widen your circle of friends and activities to fill the intellectual gaps and to dilute the boredom, frustration and resentment building up. Your husband probably feels powerless to deal with your inevitable resentment if staying with him in the same house is the only option, as you may be unable to conceal this much longer.