So scared and worried about my security

As others have said, you need to take legal advice. You can put a matrimonial Caution against the title of the property. This would stop his son from selling or mortgaging the property without notifying you so that you could challenge it and it would make the property difficult to sell or charge.
Do you have a copy of the present Will? If not, try to get one. If you put any money into the property, carry out any works etc. make sure you keep a record.

Oh my word,you Gransnetters are a mine of information. Thankyou all so much for such good guidance. The house is only in his name. Long story that still rankles to this day but he wouldn’t let me buy half. To be quite blunt, my husband thinks the sun shines out of his sons backside. Have known husband for 13 years and it’s always been the same. So first thing to do is move my money, should be able to do that even though banks aren’t up to speed. Second thing is finding a solicitor that I can actually go in and see face to face. That might take a bit longer.

It's fine having a joint account for household expenses, but you should have a bank account in your own name too.

Ask the bank whether they freeze a joint account if the one party dies, and whether funeral expenses can be paid from the deceased accounts.

If your husband ever does need to go into care and the POA comes into being, then I am quite certain your step-son will have access to all accounts, but the bank can tell you the ins and outs of that too.

Start with your bank manager, then consult a solicitor.

sorry, that should be from the deceased's accounts

Rule 1 - a joint account is never a good idea if it means you have no money in your own name in a separate account. My late husband and I had a joint account into which his salary was paid and from which all household bills were paid. I had my own money in my own account. No problems.

Rule 2 - see a solicitor and find out whether the house is in his name, or in your joint names, or whether you are tenants in common which is not the same but is the best solution. This means that when the first one dies they can leave their half of the value of the property to whoever they choose, which is usually their husband or wife. thereby giving the surviving spouse full ownership. In our case, we decided that each of our share would go directly to our daughter, so that we are now tenants in common. An unexpected bonus is that if the surviving spouse has to go into care the full value of the house cannot be used to assess the level of fees, just the half which they own.

This is so important, so do make an appointment to see a solicitor as soon as possible, as I am not sure what success you might have in disputing the will on the grounds that the son is unstable, especially as your husband has made some provision for you. The Power of Attorney is more worrying since he would in effect have control over the money you have paid into the joint account.

I would open up another joint account into which you both pay in a set amount each for bills etc.
Then change the joint accounts into sole accounts. My son & his fiance do this as they own a house together.
You may also want to ensure that your name is on the deeds too as joint owners of the house if not done already

Where were you living before you married 3 years ago? My father remarried and when he died we got nothing his wife of four years did, we never saw her again. It was as if his family and life before her never existed. I think he would not have wanted that, everything should be done legally to protect everyone. I wish now we had challenged it but we were so devasted were not able to. I think when you marry late, Tennants in Common is best then you can leave your share where you will.

Sparkling it’s HIS house. Livlass has no protection bar that offered by the trust. She has no share in the house and fears she could be bullied into moving out when her husband dies.