You can be covered under any insurance you like, it does not affect your spouse's eligibility to contribute to an HSA. You are ineligible to contribute if you are covered by any policy that is not a qualifying HDHP. Your spouse remains eligible to contribute to their HSA as long as they are only covered by a qualifying HDHP.
In other words, if you have primary coverage with your PPO and secondary coverage from your spouse's HDHP, you are ineligible to contribute. Your spouse is eligible to contribute as long as his only coverage is his HDHP and he is not secondary on your PPO. If he is secondary on your PPO, then he is ineligible.
Also note that, if your employer offers an FSA (flexible spending arrangement) and you enroll, that will also make your spouse ineligible to contribute to an HSA. By law, an FSA can be used to reimburse medical expenses for the employee or their spouse, and this counts as "other coverage" that disqualifies your spouse from making HSA contributions. The only exception is for a "limited purpose FSA" which only covers specified things that are not normally covered by insurance, such as vision care and orthodontics. You can enroll in a limited purpose FSA and that will not disqualify your spouse's HSA contributions.
Also note that your spouse can use their HSA funds to pay for your out of pocket medical expenses even if you are not eligible to make your own HSA contributions.
