I agree with everyone answering before me: You need to talk to a lender. I happen to be one...
Basically, you are going to need to add up all your "involved" expenses and divide by .4, .45 and .5.
"Involved" expenses--those which a lender will use in calculating your "Debt-to-Income" (DTI) ratio. For example: car loan, credit cards, any other loan payments, and the payment for the new home, along with the real estate taxes, homeowners' insurance premiums and any HOA dues.
You have a somewhat unique situation, in that you are trying to buy without your spouse. So, you need to consider ALL debts which you are obligated on, even if you may think of them as your husband's, but you will not get the benefit of his income. Also, Fannie and Freddie will not require your husband's credit report to be pulled, whereas FHA in a community property state such as AZ, will, but won't require you to count his debts in the DTI calculation...THOUGHT: If feasible, may consider putting loan payments into just your husband's name and then give the lenders 30-60 days to update your credit report. NEGATIVE: Closing accounts could lower your credit score, so have your Mortgage Loan Originator run a "what-if" scenario before doing so.
Anyway, divide your total debt payments by .4 to get an idea of the minimum amount of gross income you will need. Divide it by .45 to determine the realistic minimum Fannie and Freddie Mac will want you to have or you will be turned down. Divide by .5 to determine the minimum FHA will want you to be earning. For example: say you have other loan payments of $200 and your new home payments will be $800. Divide the $1,000 by .4 = $2,500 (should be no problem); .45 = $2,250 (minimum); .5 = $2,000 (just getting by on an FHA loan).
Do not have to worry about other debts, such as life insurance premiums, food, car insurance, utilities, etc. In reality, you do want to consider ALL these other "non-involved" outflows of cash, in figuring out how much you can afford to borrow, as they may tell you to be more conservative than the lender will need you to be qualify.
Your question is labeled "Home Buying in Phoenix" even though your address shows MA. Be aware Arizona is a Community Property state, unlike MA and most other states. So, for example, while I understand the GA agent's comment below about consulting an attorney for how to hold title, and you can do so if you wish, in Arizona we use Title Companies to handle that aspect. As to how to hold title, eventually you would want to get it into "Community Property With Right of Survivorship" for advantageous tax and legal reasons (in simplest terms, you decrease your taxable gain upon disposing of the home and CPWROS makes it harder for the other person to dispose of their share of the home without your permission--sad, but it happens sometimes.)
Good for you for working on your credit scores ahead of time. See my one blog on Trulia from 2/28/13 "Credit Scores and Your Mortgage Interest Rate" to see just how much you can save the higher you achieve.
Good luck. Have fun. Bill.