How do I deal with my childrens grandmother?

Ok so long story short 2 of my children’s dad died 4 years ago. At the time my children were just 6 months and 18months old. Since he died I tried my very best to keep up a relationship with his mother. We lived on the same road as her when he was alive but after him dying I couldn’t be there anymore, the house scared me, everywhere had too many memories and I was a 2 hour drive away from my nearest family member, so I decided to move back home with my dad where I had the help and support I needed. I still tried to visit his mother once a week even though the 2 hour drive there and 2 hours back was exhausting for me and my babies and being back where it happened just made me really depressed (he committed suicide, I found him).
After 6 months of visiting her weekly I broke down and refused to go back i just couldn’t cope with it, my mental health was rapidly getting worse. I explained this to her and she said visit when you feel well enough. After some time she moaned that she never sees her grand children. I explained that I still struggle being in the area and also commented on the fact that I a single mum of 2 couldn’t afford the cost of fuel to get there. She then replied with well come when you get paid next. Never once offering to help, or to come to me and visit them even though I made it clear she was always welcome to come here.
Since this happened I have met a new partner whom has helped me get my mental health back on track, I am still extremely depressed but I’m getting there. We have just had a baby.
She video calls my oldest 2 once a week but hasn’t seen them on person since I last said I couldn’t afford to get there and no longer had a running car nearly 2 years ago. She constantly moans that she misses them and it would be nice for me to bring them to see her. Again making no effort to see them herself. Since I had my baby she has stopped asking for me to take them to see her for a day and instead while on video call to them promises mummy will bring them to hers soon and they can have a sleep over for the night, expecting me to drive 8 hours in total over 2 days even though I have previously told her I couldn’t afford the fuel to drive there for 1 day. She hasn’t sent them birthday cards or presents or anything for Christmas and keeps reminding me they are waiting for me to take them to her and collect trying to manipulate me into go.

What can I do, I want my children to have a relationship with their grandmother I really do, but I want her to put effort in. If it was the other way around I would do whatever it takes to see them but she expects me to do all the work all the time. Going back there is always a set back for my mental health, its a big cost that I can’t afford but I’m expected to do it all and I just don’t think that’s fair. What should I do, I want to be a good person but I’m not a mug and if she’s not making the effort some of the time I don’t want to either.

Unfortunately, you cannot make someone want to be there