What are my rights if i am not on the title to a home?

I live in Colorado. I have been married for 5 years and moved into my wife's house because it was large enough for both my family and her family to live in. Since this was her house for the past 20 years nothing was done about putting me on the paperwork. We are now purchasing a new house. Her credit score is better than mine so we are going with that one and moving forward for approval and are getting the house. I do not any of the equity that she has accrued over the years but do want to move forward 50/50 as a partner. She is concerned that I could get what is hers if the relationship goes south... I just want to move forward after her stake with the equity has been established. She feels that me being on the paperwork will put what is hers in jeopardy. Question: Is there a legal way to move forward and put in writing that we want us to move forward 50/50 but exclude the equity which is rightfully hers? and if nothing is done do I have any rights as to what we put into the house or does it all go back to her? (I hope this makes sense) Thank you,