Am I a CF?
I'm not sure if you really want opinions, and I always try to not get involved in any arguments on the Internet if I can help it.
But yes, I still think its CF behaviour.
I am not sure how long you and DP have been together or his age or health.
But I do think it's grabby to try and stop them inheriting the house so you can stay there rent free for possibly 20 to 30 years. I.assume you are late fifties to early sixties now. You even say you chose not to get another job because you decided to live off the rental income. There is plenty you could have done to protect yourself, like get a job or get married or have something put in his will. Some would have been your choice alone, like getting a job. Others would have had to have been a joint decision like getting married. But you should have made this decisions before the move and together.
You also say he has so much money that he wouldn't want anything that is yours, but you want to keep benefitting from things your DP has spent his life working for with just a quick brush under the rug comment that your possessions are yours and nothing to do with this conversation. Happy to protect your children's assets but not so much those of his children.
You can make changes right now but you have specified several times times you don't want to do anything to help your own future, you want your DP to sort it out for you to the detriment of his own children.
You mention if it was their Mum still living in the property then they'd have to wait for their inheritance, which is ridiculous, you are not their Mum, you don't mention how long you've been together but you could just be there dad's girlfriend of 2 years which doesn't even compare in the slightest.
Would I be upset if my Mom stayed in the home she jointly owned with my Dad? No. Would I be upset that my dad's girlfriend of a few years, who hasn't worked since they moved in together and says "he has a lot of money already" wanted to stay in the family home for years? Yes.
Totally different scenarios and you definitely can't compare the two.
It doesn't really sound like you could look after the property on your small rental income, can you pay the home insurance? Council tax? What if the boiler broke? It needs a new roof? Are all these repairs something you expect his children to pay for while you continue to live rent free for possibly many years?
Legally, I am definitely no expert, but with you being a girlfriend, not married, paying nothing towards the property in any way and nothing in his will for you, I would assume you are niot entitled to remain in the home.
I can see why it would be in your best interest to remain in the property, and if the adult children aren't that close with you, again, I can see why you would choose the future that benefits you and your children the most. But I personally wouldn't think it was fair, and looking at alot of the comments you have gotten most PPs agree. But really you need to speak to your partner and he'd have to change his will to accommodate you. While I wouldn't think it was fair, the only person who's opinion matters is the legal owner of the property.