In the movie Resident Evil, Alice's husband is Matt, so who is Spencer? What about what Spencer said to her, "We can have everything"

No , you 're going the wrong way. Matt is not her husband, but Spencer, and her marriage with Spencer was fabricated by the umbrella company for them. It's a lie, because they are all employees of Umbrella Company, and they make up lies to hide people's eyes and ears and guard the entrance of the hive laboratory. Matt is a policeman and an environmentalist. He and his sister (the technician of the umbrella company) joined hands to collect the illegal research of the umbrella company. And he's the boss in Resident Evil 2.

"We can have everything" means that spence's sister wants Alice's help so that she can enter the hive laboratory to collect evidence, but their conversation was eavesdropped by spence [because they are husband and wife, although they are fake, they live together], so he went into the hive to steal viruses and wanted to sell them to the black market for money, but his memory was erased by the computer protection system of the laboratory. When his memory came back, he became greedy again. At the same time, he fell in love with Alice's beauty and wanted to turn fake marriage into reality. In short, he wants money and color.