Need some help

Why don't you ask her? Nobody here can tell you. Some will say yes, some will say no. In the end, the only way you will really have an answer is to ask her, not a bunch of strangers.

But, if it would somehow help you, I will give you my opinion. Yes, while there is breath, there is always a chance for you. You need only decide how long you wish to wait on her.

I hate it when people don't TALK to each other when there is a problem.

She already says that you don't communicate with her. THAT is the problem!1 She is waiting for you to call her and ask to sit down and discuss things. Then DO that! If need be, get a counselor or pastor to help you two communicate.

A man broke my heart one time because he could not talk about things between us. The relationship could not be put back together and it was hell for me - and him. Some time later, I'd ask myself '"what really happened?"

You have my sympathy. That relationship you two has been very important in her kids' and each of your lives. Her ex-hubby or the baby's birth daddy must have abandoned her and/or it ended badly. This must have scarred her badly and soured her about relationships. This could explain the current status.
So, she got cold feet at the thought of buying a house together and this freaked her out. Give her more understanding, more time and take time more yourself.

Be there... keep in touch...but don't pressure her. If she is calm and your calm, the right thing might happen.

Call her! She is waiting for your call, and every night crying in a pillow!

You are stating what you feel broke the relationship, you are "quiet and shy" this seems to be a big problem with a lot of women, it's sweet but they want to resolve issues, you didn't fight because you gave in and agreed but she maybe wanted your "opinion".. You say you are coming out of your shell, you know exactly what she had issues with, it takes time I know that, and she obviously to you didn't see you are "trying".

Not knowing their Dad, the children and you being there for her from the beginning, it must be so hard on you... You've taken these kids as being yours.

She's seen a side all this time that is not her, she saw you wanting to buy a house or renting it, together but she needed something more, someone who can be strong and talk... but she knows you are beautiful inside and all that you ahve done for her. You need to learn to love you, be assertive, listen, discuss, not agree... There is still hope if you can tell her, "listen" and she knows you love her but she needs to know that you don't take shirt...

In essence, you are soft, agreed with all and didn't stand your ground , know that you need to and you are working on it, but it may be too late.

Can you change over night and draw a line when it's needed, and agree when you feel it's right, instead of what ever she says goes? IDK.