It's okay to mention your late spouse, but it's best not to dwell on the topic. Your new partner is there to get to know you. Of course, your late partner influenced who you are for better and for worse, so avoiding talking about your life with them would be inauthentic. But initially, it's best not to overwhelm your new love interest with details from the past. Then, if the relationship works out, they will have plenty of time to learn more.