Big hug for you Charles.... Wow this is a lot

Depression is a serious illness and there's good treatment for it.... I would tell your wife that she needs to be referred to a psychiatrist by your family doctor if she doesn't already have one

She needs medical help.... Taking a walk won't help depression

I think unless there was serious abuse that parents and step parents need to get on the same page with kids

They're just playing one against the other ... If the 3 of you refused to trash one another and supported one another on raising the kids I think that it would solve some of this

You don't have to love the father and he doesn't have to be crazy about you and your wife.... However you can say we support your father and he supports us and it would end a lot of the manipulation

I would send her a link on the signs and symptoms of depression and let her know that YOU can't continue like this and that it's really effecting the kids and the whole family

There's good treatment..... Just as she wouldn't allow her children to stay sick and do nothing she shouldn't stay sick without doing something to help herself....

I hope that things improve for you all soon..... xo

https://www.mayoclinic.org/diseases-conditions/depression/symptoms-causes/syc-20356007

Yes, this is a lot of stuff going on and I am glad you reached out here on the forum. Sun Cloud mentioned some valid points that are worth considering so I'll go another route. The entire family is in crisis and it probably started before you came into the picture. The wife's situation may be "parental alienation" stuff, where the one parent (in your case the dad) does their best to cut the cord between the other parent and the child. Part of depression is not being able to make decisions or get out of the black hole. I am going to suggest you make an appointment with either a couples counselor, a family counselor for everyone, or a counselor for just you. Start there. Force the issue if you decide that the best thing is family or couples counseling. Talk to your wife like you have talked to us, but do not blame her (you didn't but sometimes it is so easy to go into blame mode because we don't know what else to do). Simply say the family is in crisis and we have to figure out how to fix it and you expect her to come to the appointment which is set up for blank date and time. Do it via zoom appointment if necessary. She may refuse and if so, go alone or go with just the children. Your wife getting help for her depression will not fix all the problems and she may be punishing herself for in her mind being a "bad mother" by not seeking help or creating a good life for herself. I am not saying she is a bad mother, I am saying she is telling herself she is a bad mother because of the problems with the daughter who now won't talk to her. I work with a support group for estranged parents and sometimes the women especially tend to self punish and stay in their depression - sometimes the depression was always there and the estrangement merely sealed the deal. Men will do this also, one guy recently said he didn't feel like he deserved to forgive himself. We all know humans make mistakes, the best parent in the world will make mistakes with their kids. It is a spiral - when one parent is no longer functioning effectively or positively, the kids often take on the dysfunction or get ANGRY. Please remember that the children's anger is a sign that they are UNHAPPY. If you can see them with compassion, it might help. If you will seek help, force that help, for the entire family, it could turn things around. Wishing you the very best.

What I can encourage you with, my friend, is not to let the situation change who you are. I agree that this situation was already there or brewing when you came into the scene. As you said, you were in a good place, health wise, and well-oiled machine, positive and a planner. It is hard to be the rock all the time, but be the rock all the time, anyway. Sometimes people, adults and kids, will test you. Sometimes, they resent why you are always so strong and want to see you go down. I do not know what to say about your wife but with the younger kids, one of the lessons I learned from parenting books is the impress on the them that you are on THEIR team, not the other way around. There are times when we come too strong because we want the right things to fall in place so badly. Other times they get it. I do not know about the 16 year old, she might be out of reach, but with the twins, you can still rebuild a rapport. You need to go down to their level and meet them there, peacefully and calmly. Reading some parenting books may help as well as going to a nearby church and talk to the pastor, which I did. I got support from strangers and sometimes just talking to people who are detached from the situation can help tremendously. But your main concern is to resist the slippery slope of frustration and anger, which will unravel everything you have achieved.