OP I absolutely understand you. I have no idea why anyone is giving you a hard time here! Or quibbling with how you feel.
You are a fully lone parent. I have friends in this position (for both bereavement and abandonment reasons) - and it's unbelievably tough.
Of course you are correct you have lost freedom and while many parents in couples are also pretty restricted, they can at least book in the odd weekend away or night off.
So, what I would say in practical terms is rather than focus on what is difficult is look really at whether there is anything you can do about this.
I have a husband who I am happy with so I am not in your position - however I Have SEN child with very high care needs and my husband has to work FT long hours so that I can work little/ part time to care for our child. I didn't choose this and sometimes I deeeply resent my life and what has happened to me.
I also though try to be zen! We all have our burdens - I am not comparing mine to yours, I think yours is bloody tough and as well as your burden you have your grief and loss to bear.
so - huge sympathies.
But - what you could do is small steps to consider what you could build up to in terms of freedom.
Regular playdates -where you often take other kids so that if you ever want a long day out - you can ask another mum to pick your kids up froms chool
Look on Koru Kids or similar - find after school nanny or babysitter.
iuse a babysitter more frequently than you need to build up a relationship?
Find a local mum who is great with kids whose kids are older now and is up for ad hoc childcare
I am not saying it's easy but - sometimes it helps to feel we have some control over our lives even when we have very little.
I cry tears of frustration and sadness at all I have lost because of the caring I have to do but - as I know reading your post everyone has different burdens to bear.