Weighing the options of paternity testing my kids and testing reccomendations?

I have 3 kids. My husband has questioned if he is the father to the last 2. He has let that idea go for some time now. On the other hand, it keeps coming back to haunt me. I just want to know for sure. My husband says it doesn’t matter either way and he will love them as his own no matter what and says he doesn’t need/want a test. I want to know. I feel like it would give me some closure versus me having to just wonder all the time. It is mentally straining on me. I’ve considered trying to do a test secretly so I’m the only one who knows about it. Is it going to be worse if Ive seen the test results and then have to keep that a secret or should I just spend the rest of the time not knowing and always wondering for the sake of everyone’s sanity except for my own…? I’m very conflicted on what to do and feel a little selfish that I want to confirm paternity. Anyone have any good advice, experience or thoughts on this? Was considering doing a sibling test because I’m positive my oldest is his so that would be able to confirm dna with the others unless I can find a way to secretly get a dna sample???