Honestly, it sounds like form most of your posts, you are not happy either but want it to work.
First off, you can't change someone unless they want to change themselves. She does have 3 kids to raise and that is hard enough. She is lucky inthe sense that you seem like a great husband, But arde you posting all these questions while you two are home? When the kids are there? Why aren't you doing family things together? Sounds like your existance has gotten in a boring routine. You need to stay of the computer and heal this marriage. If she isn't willing to meet you half way, then it's safe to say it's time to go.
You either must take it, or leave it. Cause it seems you can't change her. Only moments together will cause change, not just saying hey do this. Give her a reason to, and visa versa. Maybe you do need to spend mroe time with your family and help out, some anyway. If you are tired, relax a bit, but children grow so fast, and time can slip away when you spend alot of time on the computer.. That may be part of the problem. Material things don't matter... It's what goes into the heart!