I would really stress the importance of having an open one-on-one conversation with her and resolve these issues. Seems like you already tried that and it turned into a heated discussion, here is some advice on how to approach it.
1. Have the conversation in a public place where professionals meet. For example, coffee shops. If you in the bay area, it would be best to have it in coffee shops known for startup discussions, such as Coupa Coffee in Palo Alto. Just choosing the right place for the conversation will make sure that the discussion does not go out of hand.
2. Come to the discussion with an open frame of mind. There may be some issues that she is feeling - you should be willing to listen.
3. Alert her in advance about the general topic you want to talk about. So that she is not surprised and is mentally prepared.
4. During the discussion, make sure to lay out specific behaviors/situations/examples that you find objectionable, and listen to what she has to say. Again, be open - perhaps there is another piece of the puzzle here that you have thought about fully, and she explains it to you.
Example: "I put in 60-70 hours per week" is a very general statement. A specific statement would be "Last week, we launched feature F. I did X, Y, Z tasks over night to make the launch successful. However, you contribution over that week was only implementing a simple bug fix B. I would like to listen to you to know how can I help you contribute more to the project."
5. You may have some counterpoints to the arguments she makes. Be specific and encourage her to be specific. Hopefully after some time you'll sort it out amicably and you both have a good understanding of how each other works.
6. Contrary to what others have said, I would not bring a third-party to the discussion. You need to own resolving this problem. Getting third-party involved too quickly can be detrimental - they don't know the situation as much as both of you do. Most problems like these can be solved by honest and open communication.
1. Have the conversation in a public place where professionals meet. For example, coffee shops. If you in the bay area, it would be best to have it in coffee shops known for startup discussions, such as Coupa Coffee in Palo Alto. Just choosing the right place for the conversation will make sure that the discussion does not go out of hand. 2. Come to the discussion with an open frame of mind. There may be some issues that she is feeling - you should be willing to listen. 3. Alert her in advance about the general topic you want to talk about. So that she is not surprised and is mentally prepared. 4. During the discussion, make sure to lay out specific behaviors/situations/examples that you find objectionable, and listen to what she has to say. Again, be open - perhaps there is another piece of the puzzle here that you have thought about fully, and she explains it to you. Example: "I put in 60-70 hours per week" is a very general statement. A specific statement would be "Last week, we launched feature F. I did X, Y, Z tasks over night to make the launch successful. However, you contribution over that week was only implementing a simple bug fix B. I would like to listen to you to know how can I help you contribute more to the project." 5. You may have some counterpoints to the arguments she makes. Be specific and encourage her to be specific. Hopefully after some time you'll sort it out amicably and you both have a good understanding of how each other works. 6. Contrary to what others have said, I would not bring a third-party to the discussion. You need to own resolving this problem. Getting third-party involved too quickly can be detrimental - they don't know the situation as much as both of you do. Most problems like these can be solved by honest and open communication.
Good luck!